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40 The PCB Magazine • October 2014 ed to a HAST test at +130°C with 85% humidity level. The results obtained from reliability test- ing are summarized and compared within this paper. The identified relations between manu- facturing technology and the reliability perfor- mance of the test vehicles are shown; strengths as well as weaknesses of the applied any-layer technologies are identified and summarized. Introduction IBM's introduction of the IBM Simon Person- al Communicator marks the beginning of the smartphone era [1] . Combining phone functions with the functionality of a PDA is a remarkable milestone for our communication age. Howev- er, while being very innovative, the device was not really suitable for one's waistcoat pocket. With a total weight of 510 g and a thickness of 38 mm, it was confined to in the briefcases of business executives. Since that time, the smart- phone OEMS have quite clearly recognized that next to functionality the handling behavior and the ergonomics of the smartphone device belong to the decisive criteria for the custom- ers. Based on selected examples, Figure 1 shows how the smartphone dimensions have evolved since Simon appeared. While the basic length and width of the devices just changed with re- gard to functional and aesthetic trends, the re- duction of the thickness of a smartphone device became a kind of race, with the OEMs as com- petitors. As Figure 1 shows, the thickness of a smartphone device has been reduced by a factor of almost six, with the October 2012 champi- on being the Finder X907 device from Chinese OEM Oppo. This Android-driven device claims to have a nominal thickness of only 6.65 mm. However, there will not be much time to enjoy the position at the cutting edge since another Chinese OEM, ZTE, already announced the in- troduction of a device with 6.2 mm within the next months. In order to achieve this reduction, the smart- phone designers quite neatly used all the possi- bilities that the always ongoing miniaturization THIN PCBS FOR SMARTPHONES continues figure 1: thickness of smartphone devices with regard to the year of introduction.