The plastic packaging process for integrated circuits is subject to several fabrication defects. For packages containing leadframes, three major defects may occur in the molding process alone, namely, incomplete filling and void formation, wire sweep, and paddle shift. Paddle shift is the deflection of the leadframe pad and die. Excessive paddle shift reduces the encapsulation protection for the components and may result in failures due to excessive wire sweep. Computer-aided analysis is one of the tools that could be used to simulate and predict the occurrence of such molding-process-induced defects, even prior to the commencement of mass production of a component. This paper presents a methodology for computational modeling and prediction of paddle shift during the molding process. The methodology is based on modeling the flow of the polymer melt around the leadframe and paddle during the filling process, and extracting the pressure loading induced by the flow on the paddle. The pressure loading at different times during the filling process is then supplied to a three-dimensional, static, structural analysis module to determine the corresponding paddle deflections at those times. The paper outlines the procedures used to define the relevant geometries and to generate the meshes in the “fluid” and “structural” subdomains, and to ensure the compatibility of these meshes for the transfer of pressure loadings. Results are shown for a full paddle shift simulation. The effect on the overall model performance of different element types for the mold-filling analysis and the structural analysis is also investigated and discussed. In order to obtain more accurate results and in a shorter computational time for the combined (fluid and structural) paddle shift analysis, it was found that higher-order elements, such as hexahedra or prisms, are more suitable than tetrahedra.
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e-mail: jimppl@mail.ncku.edu.tw
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September 2005
Research Papers
Three-Dimensional Paddle Shift Modeling for IC Packaging
Chien-Chang Pei,
Chien-Chang Pei
Graduate Student
Department of Mechanical Engineering,
National Cheng Kung University
, Tainan, Taiwan
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Sheng-Jye Hwang
Sheng-Jye Hwang
Associate Professor
Mem. ASME
Department of Mechanical Engineering,
e-mail: jimppl@mail.ncku.edu.tw
National Cheng Kung University
, Tainan, Taiwan
Search for other works by this author on:
Chien-Chang Pei
Graduate Student
Department of Mechanical Engineering,
National Cheng Kung University
, Tainan, Taiwan
Sheng-Jye Hwang
Associate Professor
Mem. ASME
Department of Mechanical Engineering,
National Cheng Kung University
, Tainan, Taiwane-mail: jimppl@mail.ncku.edu.tw
J. Electron. Packag. Sep 2005, 127(3): 324-334 (11 pages)
Published Online: December 2, 2004
Article history
Received:
April 19, 2004
Revised:
December 2, 2004
Citation
Pei, C., and Hwang, S. (December 2, 2004). "Three-Dimensional Paddle Shift Modeling for IC Packaging." ASME. J. Electron. Packag. September 2005; 127(3): 324–334. https://doi.org/10.1115/1.1938986
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