The principle of surface insulation resistance (SIR) testing and its role in establishing the electrochemical reliability of a printed circuit board

Many people have heard the abbreviation SIR but many people wonder what it actually means. This paper introduces and explains the concept of surface insulation resistance (SIR) testing, and shows how the test method can be used to establish the electrochemical reliability of an assembled circuit using a more environmentally acceptable production process. A means of extending this test methodology to include process control is be presented and discussed.