In-mould integration of electronics into mechanics and reliability of overmoulded electronic and optoelectronic components

Next generation of smart systems in different application areas such as automotive, medical and consumer electronics will utilize various electronic, optical and mechanical functions integrated in plastic product structures. In this study, in-mould integration of electronic and optoelectronic modules is examined in order to embed novel functionality into polymer matrix. Thermal load of the electronic components embedded in polymer material was briefly modelled, and a series of test structure samples realized. The test structure consisted of a flexible printed circuit (FPC) substrate with assembled electronic and optoelectronic components, which was set as an insert into injection moulding mould and thermoplastic polymer was cast on the substrate in injection moulding process. After the over moulding of the samples, characterization of components was carried out by visual inspection and by functional testing. It was found out that with correct injection moulding process parameters, all components survived the challenging conditions of injection moulding process. The reliability of the samples was evaluated by subjecting them to constant humidity test +85degC/ 85% RH and -40degC ... +85degC temperature cycling test. After the tests, the samples were analyzed by visual inspection, functional testing and cross-sections. The analysis revealed that when using an appropriate silver paste, over 90% of the components remained functional, although problems were observed in the adhesion between the FPC substrate and the over moulding material.