On the basis of the industrial research and development work carried out in the project, procedures for handling substrates and electronic components will be developed, as well as technologies for assembling electronic systems, dedicated to various structural solutions of FLEX flexible substrates, which will meet standards for critical applications. A specification for the assembly of flexible substrates will be developed, new procedures for storage and preparation of substrates and electronic components after delivery and during production processes, testing and selection of soldering materials and process parameters for soldering, washing, laser cutting, coating. Resistance to external conditions for constructional solutions of flexible assemblies - vibrations, temperature, humidity, overload will be examined. The conducted tests should also give an answer as to which FLEX construction solutions can be used in less critical applications.