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|Development of Simulation Tool to Predict Deflection of Small-Sized Chip by Wire Bonding USG|
|Keywords: Force Transimissibility, DAF Shear Modulus, USG|
|When wire-bonding process is progressing, a chip makes vibration because of the USG current which generates the force parallel to the chip. This phenomenon is more severe in small-sized chip (ex. Controller) by generating larger deflection. Because of larger deflection, bonded wire ball spreads on the pad, and it contacts with other adjacent wire balls. It makes the wire ball-short issue. This issue can be critical bacause the chip size is getting smaller by increasing the net-die of wafer, so we need to suggest the proper design guide applied to wire-bondding of small-sized chip. In this study, To describe the small-sized chip deflection by USG current, Mathmatical model is suggested in two points of view. First, we derived the 2DOF(Degree-Of-Freedom) vibration model computing the force transmitted to top side of the DAF by applying the theory of vibration force transmissibility. Because the USG current transmits the force shaped sine wave to the chip. Second, DAF Deflection generated by the force transmitted to top side of the DAF was derived by applying the theory of mechanics of materials. To compute the DAF Deflection, The Shear Modulus is measured for 3 Types(low, mid, high modulus) of DAF. This study suggests the design rule that the edge deflection of the chip is under 1.0um. This suggestion is caused by the reduction of the rate for the wire ball short failure.|
|Jongwan Kim, Assembly Process Development
Asan, Chung nam