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In recent years, a growing number of electronic devices are being incorporated into automotive and other high reliability end products with the challenge to make these devices more reliable. The package size of the devices is largely driven by the consumer industry with their sizes getting smaller making it harder to assemble and be reliable at the same time. For automotive and other high reliability electronics product, it is of the utmost priority to secure high reliability because it directly involves human life and safety. Challenges include selecting an appropriate solder alloy and having good reliability of the solder paste flux residue with the presentation discussing ways to improve lead-free solder joint reliability/robustness. Though SnAgCu solder alloys fulfill most soldering requirements, alternative solders are needed to meet more stringent environmental regulations, requirements for greater mechanical reliability, and more demanding high temperature service environments such as under the-hood in automobiles and in avionics systems. Development was done on alternative lead-free alloys with varying percentages of tin-silver-bismuth-indium in comparison with a number of conventional lead-free solder alloys in soldering evaluations. Accelerated thermal cycling test was performed on boards assembled with various different alternative alloys and the results were compared with conventional lead-free alloys. For the solder paste flux, there is a need in automotive and other high reliability applications to have reliable and high insulation resistance even in an atmosphere of high temperature and high humidity. Development was done on a type of ‘crack free’ flux paste to inhibit flux residue cracking under extreme environments making it more reliable to stringent surface insulation resistance and electro-migration criterion from automotive and other high reliability product manufacturers. Testing was done to various industry electro-migration and dew test standards.