Ye Lezhi

Study on bumps deformation of flip chip bonding process

The flip chip package is an advanced chip interconnection technology, which has become a main technology of high density package. This paper mainly studies the influence of bumps deformation in the flip chip bonding process on connection reliability, which provides theoretical reference for the flip bonding process. Bumps deformation is a key factor for the chip reliable connection in the flip chip bonding. Bonding force directly determines the bumps deformation. The quality of the bumps will affect the reliability of reflow soldering and under-fill processes. This paper builds a three-dimensional model of flip chip bonding. By the FEM simulation analysis, the relationship between bonding force and bumps deformation is studied. The process parameters are optimized by comparing the experimental data with simulation result. Finally, the reliability evaluation method of flip chip bonding is obtained, which can be used to guide the research and development of the bonding equipment.

Light extraction analysis of high-power LED based on flip chip technology

The light extraction has an important effect on LED encapsulation to obtain a high efficiency. The influence of packaging structure on LED light extraction was investigated in TracePro. Four kinds of high-power LED packaging methods based on the structure and the character of flip chip were presented, flip chip on board (1 reflective-cup), flip chip to substrate (1 reflective-cup), flip chip on board (100 reflective-cups) and flip chip to substrate (100 reflective-cups). Flip chip on board was that the LED chip was directly bonded to the aluminum substrate, flip chip to substrate was the LED chip bonded to the Si-Substrate before bonded to the aluminum. Two different structures of aluminum substrate were analyzed, 1 substrate with only 1 reflective cup and 1 substrate with 100 reflective cups. The final result shows that the luminous efficiency of flip chip on board (100 reflective-cups) is 0.03% higher than flip chip to substrate (100 reflective-cups); luminous efficiency of flip chip on board (1 reflective-cup1) is 0.04% lower than flip chip to substrate(1 reflective-cup). Luminous efficiency of flip chip on board (100 reflective-cups) is 10% higher than flip chip on board(1 reflective-cups); luminous efficiency of flip chip to substrate (100 reflective-cups) is 6.3% higher than flip chip to substrate(1 reflective-cup).

Research and development of expert system for permanent magnet retarder design

The basic principle, structure, and function of an expert system for designing permanent magnet retarder (PMR) is described. The system takes into account the preliminary design process and has been achieved with a high interactivity level. The frame structure and work mode of the platform are introduced by analyzing function modules. The main parameters of the PMR structure are designed using robust optimization techniques. The functions of the simulation analysis and virtual assembly module are discussed. The expert system of the technology integration is developed.