What is BS EN IEC 61189-5-503- CAF testing of circuit board about?  
BS EN IEC 61189 covers test methods for electrical materials, printed boards, and other interconnection structures and assemblies. The main objective of the IEC 61189 series is to demonstrate the reliability of laminate materials and assemblies and avoid printed circuit board failures.
BS EN IEC 61189-5-503 is an international standard for electric materials that specifies the test methods for materials and assemblies which is helpful in measuring the ionic residues which are dissolved in ionic contamination solutions.  
BS EN IEC 61189-5-503 the conductive anodic filament (hereafter referred to as CAF) and specifies not only the steady-state temperature and humidity test but also a temperature-humidity cyclic test and an unsaturated pressurized vapor test (HAST).
Who is BS EN IEC 61189-5-503 - CAF testing of circuit boards for? 
BS EN IEC 61189-5-503 on CAF testing is relevant to:
- Manufacturers of electronic devices
- Manufacturers of printed circuits and boards
- Quality testing agencies
- Electronics industry
- Electronic engineers
Why should you use BS EN IEC 61189-5-503- CAF testing of circuit boards?
CAF is defined as migration which occurs along the monofilament of reinforcing material such as glass cloth in an inner layer part of a printed wiring board.
BS EN IEC 61189-5-503-compliant test board designs for evaluating CAF resistance you can ensure that surface insulation resistance failures do not occur.
The temperature and humidity test recommended by BS EN IEC 61189-5-503 is implemented to ensure or verify the ability to maintain the service life if the specimen is used under constant temperature and humidity conditions. This helps you to review the test conditions and to pay sufficient attention to high-temperature conditions.
BS EN IEC 61189-5-503 evaluates resistance of the board to electrical insulation degradation and resistance to migration under the temperature and humidity cyclic test with and without lowtemperature exposure. It is an effective test to confirm the durability of the products in environments with varying temperature and humidity.
BS EN IEC 611895--503 enables an accelerated evaluation of insulation deterioration of material by forced moisture absorption, resistance to migration, comparison of material characteristics, lot reliability, moisture-proof reliability for the insulating film (solder resist, etc.), and other performance degradations.
Overall, BS EN IEC 61189-5-503 can demonstrate the reliability and performance of a printed circuit board laminate material or a finished product. Events of electrochemical migration and consequent PCB failures can thus be avoided.
