Effects of operating conditions on automotive electronics

Electronics is already established as an integral part of modern vehicles. In order to enforce recycling and recovery of vehicles, the End-of-Life Vehicles legislation was developed in the EU. This directive includes bans for certain substances (especially lead). Compared to the lead-free soldering the assembly of electronic devices using electrically conductive adhesives (ECAs) has a number of technological differences. This paper presents the results of experiments with the effect of dry heat, moist heat and temperature cycles on electrically conductive adhesive joints. Accelerated reliability tests have been focused on aspects of the assembly process on a test PCB using one-component and two-component ECAs. According to our measurements, ECAs are generally highly sensitive to harsh environment. In all experiments better reliability of two-component adhesive was observed. The least dangerous type of climatic load for ECAs is a dry heat. During temperature cycles structural changes of the joints made with one-component adhesive AX 20 were observed. Although the change of measured electrical resistance of these joints was relatively small (6%), temperature cycling provoked creation of cracks in all the joints. Acquired data will be further used to design complex accelerated reliability tests.