Investigating test methods for electrochemical consistency in PCB assembly processes

There are several methods accepted by the industry for determining the electrochemical reliability for electronic assemblies. These methods are typically designed to either simulate humid environments in accelerated lifetime testing, or assess the species of ionic residues present on surfaces. Some can be used to test prototypes or test boards; others are more applicable for quality and consistency testing in a production environment. The increasing complexity of high density assemblies, along with low standoff components, imposes greater associated challenges related to assessing electrochemical reliability. This has led to development and adoption of new methods for testing ionic residues that can lead to electrochemical migration. This paper will review traditional and emerging methods to characterize flux residues and cleanliness of finished assemblies, including surface insulation resistance, electrochemical migration, ROSE extraction, and other emerging test methods. Data will be shared showing how different methods can detect process variations in different ways, results will be compared.