Research On The Reliability Of Package-On-Package In Different Temperature Environment

Due to the rapid development of information technology, the semiconductor industry has increasingly made continuous progress. As an important part of the semiconductor industry, package testing plays a crucial role in the overall performance and quality of IC products. Nowadays, with the continuous development of mobile electronics market, a lot of consumer electronics products are involved in the package type of POP(package-on-package), such as mobile phones, tablet PC, cameras and the reliability of POP has gotten more and more attention. Numerous new products require to improve the performance and reduce the size. The presence of the POP has met the requirements of new products and begins to obtain extensive application. Because of the unceasing increase in packaging density, heat accumulation will affect its reliability in the use process of the electronic products. It was studied the reliability of POP in the temperature environment in this paper. The following works were done:We used experiment method to test the strain properties of the 14 mm POP in thermal shock environment, and concluded the strain values of the top and bottom solder joints. We also tested 14 mm and 15 mm POP in the off-line coupling environment of temperature cycle and thermal shock, and concluded the strain values of the top and bottom solder joints.Regardless of the thermal shock or offline coupling environment, the strain of POP top and bottom solder joints presents periodic change, and the strain of the top solder joints is bigger than the bottom. According to the strain values, we can obtain the reliability life of the solder joints. Through the finite element simulation analysis of the POP in the thermal shock environment, the stress is mainly concentrated in the solder joints and chips. The maximum stress of bottom chip is larger than both the top chips. The stress of the bottom solder joints is greater than the top solder joints, and the maximum stress of bottom solder joint is at the corner of the outer ring solder joints.This paper compared and analyzed the strain of the same chip under thermal shock and off-line coupling environment. The solder joints strain under the thermal shock starts from0, and that under the off-line coupling environment has a starting value, which shows that there is residual stress made by temperature cycle under the offline coupling environment.The solder joint strain under offline coupling environment is greater than the solder joint strain under the thermal shock environment. We made comparison of the test results ofdifferent size POP under the same off-line coupling environment. Both the strain of 14 mm POP and 15 mm POP have a starting value, and the strain of 15 mm POP is greater than14 mm POP. The difference of strain between them is more obvious especially in the temperature change stage, which may be induced by the different of solid joints and size about the POP.In summary, it was used the method of experimental test and simulation to analyze the reliability of POP in the temperature environment. We made comparison of the reliability of the same size POP under two different temperature conditions, and two different size POPs under the same temperature condition. At the same time, it was made a comparison of the experimental results and the simulation results, which verified the correctness of the model. The analysis results can provide reference for POP testing and reliability research in the future.