关键词: 微焊点, 尺寸效应, 界面反应, 工艺优化

Abstract: This article focuses on the high-density and high integration packaging requirements of new generation aerospace integrated circuits such as 2.5D integrated products, and conducts research on injection molding module flip chip technology based on pressure reflow. Research has shown that injection molding modules and substrates exhibit similar warpage trends and changes in warpage direction. The main source of module warping is the expansion of injected plastic after reaching temperatures above Tg. The interlayer and intralayer differences of multi-layer wiring on a substrate are the main source of local warpage differences in the substrate. Comparing the shape and simulation results of pressure reflow solder joints under different working conditions such as no fixture, gravity pressure block, and limit fixture, it is found that there is a significant risk of virtual soldering in reflow soldering without fixture. Gravity pressure block and limit fixture can effectively eliminate virtual soldering of solder joints, but under limit fixture working conditions, solder joints have a higher height. Through high-density integrated micro interconnect structure multi field coupling constitutive modeling and finite element life simulation based on cross scale sub models, the fatigue life of solder joints was calculated to be 3390 times. The reliability assessment of multi stress shows that 2.5D chip integrated flip chip devices can pass reliability assessments such as screening, identification of D3 and D4 grouping, high-temperature storage, temperature cycling, solder heat resistance, and HAST. Effectively solved the problems of flip chip bump virtual soldering and bridging caused by reflow warping of injection molding modules and LTCC substrates, providing packaging technology support for the development of 2.5D integrated products for major aerospace projects.

Key words: micro solder joints, Size effect, Interface response, process optimization