We propose a new method of consolidating a disjointed simulation environment for the development or design of cellular phone terminals. The resulting environment was applicable to each phase, especially the early phase, in which simulation tools for development TAT improvement had been considered impractical. The simulation environment was designed to include electrical CAD and mechanical CAD environments. Libraries were consolidated into a common analysis library and a common model library, which simultaneously helped to improve accuracy and analysis time, so that the simulation environment become practically applicable to actual development stages. Examples of practical development scenes, such as an antenna performance analysis, an EMI countermeasure design, a pressure durability evaluation, and a thermal radiation analysis demonstrated the effectiveness of our proposed environment. By introducing the new environment, we could reduce the total development period, including prototyping, from 18 months to 10 months (the contribution of each was 15%, 38%, 27%, and 40%, respectively).

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Spontaneous whisker formation from pure tin and tin-based finishes on copper leadframes at ambient temperatures is a major concern before board assembly of electronic devices. In this study, significantly different tendencies of whisker formation were found from the same tin–copper (Sn–Cu) coating electrodeposited on two different copper leadframes, namely, copper–iron (hereafter, CUFE; corresponding to CDA number C19400) and copper–chromium (CUCR; CDA number C18045). After long-term storage at room temperature, no whisker formation occurred from the Sn–Cu coating on the CUCR leadframe, whereas long whiskers, with a maximum length of more than 200μm, were formed from the Sn–Cu coating on the CUFE leadframe. Microstructural FE-STEM/FE-TEM/EBSP characterizations at vertical cross-sections of the Sn–Cu coated leadframes, an XRD stress measurement of the coatings, an FEA analysis of coating stress distributions, a molecular-dynamics simulation of atom diffusion in the coating, and an investigation of the correlation between whisker roots and coating microstructures using a planar slicing method were performed for the two aforementioned samples. The results of these examinations clarified the mechanisms of the formation and suppression of whiskers grown from the Sn–Cu coating, and we established a countermeasure against the spontaneous whisker formation through the selection of the copper leadframe material.

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