Contact beam structures for fine pitch (0.5-mm) test socket thatwill mate with 95/5 lead/tin solder balls (50±5 μm indiameter) were fabricated by conventional integrated circuit processingtechnology. A range of dimensions for contact beam structure (cross andbridge) were tested for mechanical behavior and electrical performance.Non-linear finite element models (ANSYS 5.5) were used to predict theforce and stress between the copper thin film beam structure and thesolder ball. To avoid plastic deformation of the solder ball, numericalanalysis suggests that the contact force on 50 μm solder balls shouldbe lower than 17 mN. The yield strength of sputtered copper thin film (2μm) is inferred from experimental and numerical data to be in therange of 2.80-3.09 GPa. The best cross and bridge structures arepresented in addition to a new “Meander” structure which,numerically, shows the best potential
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