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Reliability on 2.5D IC package is a big concern and challenge due to complicated packaging structure and high reliable requirement. Underfill failure such as delamination and cracking is one of common failure modes in 2.5D IC package when package is subjected to thermal aging condition. Underfill cracking occurs for 2.5D IC package with TSV interposer after high temperature storage (HTS) test. Failure mechanism is determined based on material characterization on underfill. Testing results show that underfill shrinkage increases with increasing HTS duration and interfacial strength of underfill/silicon decreases with increasing HTS duration. Thermal aging induced underfill shrinkage and interfacial strength degradation are main reasons resulting in failure. Finite element analysis (FEA) is conducted with modeling thermal induced shrinkage for 2.5D package under HTS condition. The predicted failure and location of underfill cracking is consistent with experimental observation when applying the developed new FEA model and material properties.

When the gait feature is recognized, it will be hard to meet the real-time need due to the complexity and long calculated time of the recognition algorithm. Under this circumstance, a novel sparse representation based human gait recognition method is put forth which is based on. First of all, human silhouette is established and gait period is calculated. Next, we adopt Shifting Energy Image (SEI) as the feature of image and then extract Gabor Wavelet and Local Binary Pattern features. Finally, gait feature will be classified and recognized by using sparse representation. CASIA B gait database will be used in the experiment with a view of 90 degrees. The result witnesses that this method has higher recognition rate and can meet the needs of real-time.

This paper focused on the delamination study of low profile leadframe package with exposed pad (eLQFP). In this type of package, a specification of silver plating area is required for bond pad. With the shrinkage of the non-plating pad area, and because of low adhesion strength between silver and mold compound, the interface of mold compound and die-pad in the silver plating area may potentially delaminate especially after moisture sensitivity level 3 test (MSL3) and IR reflow. The study is to define a design guideline and mold compound selection rule for minimum delamination after MSL3 & IR reflow. Firstly, a safety factor K is defined as delamination guideline. Then the structure parameters were prioritized for their impact to the factor K. Thirdly, a DOE was carried out to study the mold compound property effect on the delamination. Guided by the simulation in structure and mold compound study, a group of test vehicles were designed to validate the reliability. The result shows the well-defined safety factor K was workable for eLQFP failure evaluation.