High Density Interconnect (HDI) Socket Dynamic Warpage Prediction by Mori-Tanaka Model

High-density interconnect (HDI) sockets, primarily designed for CPUs and GPUs, are shifting towards larger form factors as the number of interconnect pins increases. The dynamic warpage prediction and control during reflow onto the printed circuit board is the main challenges for large socket. The liquid crystal polymer (LCP) material used in the socket manufacturing exhibited an anisotropic behaviour due to mixture of inherently anisotropic polymer matrix with anisotropic fillers, as compared to general plastics. Socket warpage may under or over predict with standard composite model assumption. This was attributed to the polymer matrix, which was assumed to be a homogeneous material within the composite model. Thus, a new Mori-Tanaka mechanics model was investigated as it has the capabilities to incorporate both polymer matrix and fillers anisotropic effect. A commercial injection molding simulation tool, Moldex3D was employed and validated with experimental measurements. Composite model recorded a larger prediction variation for both room temperature (RT) and high temperature (HT) warpage. In comparison, Mori-Tanaka model predicted better RT and HT comparison, and with good correlation (R<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup>>0.8) obtained. Thus, this studied has demonstrated a new modelling methodology to improve prediction accuracy.