The Study On Reliability Of Three-dimensional Stacked Die Package

With the development of electronic technology, three-dimensional packaging is developed to meet the requirements of smaller size and higher density package. Stacked die package is a widely used three-dimensional packaging technology, it improves the density of electronic products, reduces the interconnect wire length between the chips, increases the operating speed of the device and achieved multifunction in a device. But the rapid increase in integration density electronic packaging is bound to higher requirement of thermal conductivity, dielectric properties, performance of packaging materials. So, it requires development of new packaging materials and technologies. At the same time, electronic components are hosted by higher mechanical, thermal, electrical stress, so the study on reliability of stacked die package is more and more important.Stacked die package needs to multiple chips vertically, the adhesive between chips, chips and lead frame, chips and the plastic material and interconnection is the key. In this paper, the way to achieve interconnection is wire bonding. In order to avoid major changes to the packaging process, reduce the thickness of the stacked die to ensure that the overall package thickness unchanged. However, reducing the thickness of the chips will cause the chip to reduce the stiffness. Deformation easily occur during heat treatment, it may cause die chipping and crack. Further, due to the reduced thickness of the plastic, the ability to prevent moisture intrusion in interface of material will be reduced and will lead to delamination and cracks. This paper design parameters for the experiment based on these conclusions after analyzing the characteristics of the stacked die package.This paper designed stacked die packaging process, selected materials and equipments based on mature TSOP(Thin Small Outline Package) packaging technology, used conventional epoxy resins and epoxy film as adhesive materials. Then through packaging process control plan, tracked the failure mode in the process, used X-rays and C-SAM testing after the completion of process, further confirmed the failure mechanism of stacked die package. Then, proposed improvement of the stacked die package process based on the conclusion. Finally, use good stacked die package samples of the two groups for reliability test, including pre-condition test, constant temperature and humidity testing, non-biased high-speed accelerated stress testing, temperature cycling and high temperature storage test, analyzed the failure mechanism of the delamination, and proposed optimization of product reliability.