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58 SMT Magazine • November 2014 could be seen between SAC and SnPb alloys. Analysis of the data showed that, depending on the test vehicle configuration and the test conditions in some cases, SAC alloys gave im- proved reliability over SnPb alloys and in other examples the reverse result occurred. This test- ing focussed on environmen tal conditions rep- resentative of the bulk of the electronics indus- try at that moment in time (-40°C to +125°C). More recent developments in electronics, espe- cially within the automotive sector have pushed these requirements to increasingly harsher test conditions, with 150°C maximum temperature becoming the norm and the number of thermal cycles increasing from 2000–3000 [4] . In addition, to the increasing environmental conditions, the number of printed circuit boards (PCBs) per vehicle and complexity thereof has increased significantly over the past 10 years as demon- strated in Figure 1. This increased thermal cy- cle resistance requirement in conjunction with the expansion of the life-critical nature of the electronics systems within a standard vehicle (ABS, ESP, airbag sensors, lane departure, crash prediction, etc.) has driven the development of improved lead-free alloys for high-reliability applications. In addition to this, reductions in available space and requirements for increased functionality have driven PCB designers to look at component miniaturisation and finer-pitch devices. This is the same trend that was observed in the telecommunications sector over the past 15–20 years. The effect of placing components closer together in harsh environmental condi - tions has increased the focus on developing fluxing systems with better electrical reliability. The combination of alloy developments that in- crease the PCBs time to mechanical failure and flux technology that reduces electrochemical failure mechanisms has provided a synergistic system ideally suited for the demands of mod- ern, high-reliability electronics. HigH-reLiabiLity, Pb-Free, HaLogen-Free soLDer continues arTiCle figure 1: general trends in automotive electronics.