Study on Wire Sweep and Warpage Problem of IC Package

• Main Authors: Liu, Wen-shu, 呂文述
• Other Authors: E. N. Pan
• Format: Others
• Language: zh-TW
• Published: 1998
• Online Access: http://ndltd.ncl.edu.tw/handle/60577650077769599187

碩士 === 國立臺灣大學 === 機械工程學系研究所 === 86 === During IC encapsulation filling process, the epoxy would exert drag force on wires and cause wire sweep. If the neighbor wires touch, short-circuit occur. With the trend of more wires, less wire distance and thinner the cavity depth, wire sweep problem would become serious and critical. We observe the flow pattern and wire sweep in different mold cavity shape with flow visualization facility. We also investigate the influence of various parameters in TCCM (Transfer Charged Compression Molding). With the same Reynolds number. The wire sweep is larger in circular mold cavity than that in square cavity. During the same filling time. The wire sweep difference between circular cavity and square cavity is not very significant. During TCCM process. The wire sweep becomes larger with faster compression speed and larger compression ratio. We could introduce higher flow rate and would not cause serious wire sweep. PBGA (Plastic Ball Grid Array) is a rising and popular IC packaging technology. However, due to its unsymmetrical shape and the difference of CTE between its consisted components. PBGA is easy to warp during thermal cycling. It’ll reduce it yield. This study use ANSYS to analyze warp of PBGA during thermal convection by building up various 3D finite element model, changing EMC shape and adding ribs on it. We conclude that adding ribs on square EMC would enhance the stiffness of PBGA during thermal cycling, but circular EMC do not have significant effect.