Chemical Shrinkage and Viscoelasticity for Molded Underfill
The molded underfill (MUF) offers many unique advantages, including lower material costs, higher throughput, and excellent reliability for flip-chip chip scale packages (fcCSP) and fan-out packages. The assembly process yield and reliability of these packages are significantly influenced by the warpage behaviors of MUF. We develop an integrated process modeling approach incorporated with real-time chemical shrinkage and cure-dependent viscoelastic constitutive model for warpage prediction. The cure-dependent chemical shrinkage, kinetics and viscoelasticity are measured using pressure-volume-temperature (PVT) method, differential scanning calorimetry (DSC) and dynamic mechanical analysis (DMA). The integrated model is applied to fcCSP and fan-out packages with different designs, and the simulation results are in good agreement with the experimental data. A simplified model is also constructed for MUF with a fast corss-linking rate. In addition to warpage prediction, we successfully demonstrate that the model is useful to select suitable MUF baseline materials. authors: Shu-Shen Yeh, Po-Yao Lin, Kuang-Chun Lee, Jin-Hua Wang, Wen-Yi Lin, Ming-Chih Yew, Po-Chen Lai, Chia-Kuei Hsu, Che-Chia Yang, Shin-Puu Jeng
Interconnect
Interconnect
Interconnect is critically important for system performance. They are structures that connect two or more circuit elements (such as transistors) together electrically. In the past, interconnect was often referred to as on-chip interconnect of integrated circuits. Nowadays interconnect generally includes both on-chip interconnect of integrated circuits and off-chip interconnect in heterogeneous system integration. In interconnect design, geometric dimensions (width, thickness, spacing, aspect ratio, pitch), materials, process control and design layout are all critical to proper interconnect function, performance, power efficiency, reliability, and fabrication yield.
