Effect of thermal interface materials on manufacturing and reliability of Flip Chip PBGA and SiP packages

Author(s):  
Li Li ◽  
Mohan Nagar ◽  
Jie Xue
2000 ◽  
Author(s):  
Amit Devpura ◽  
Patrick E. Phelan ◽  
Ravi S. Prasher

Abstract An important aspect in electronic packaging is the heat dissipation. Flip-chip technology is widely being used to increase the rate of heat transfer from the chip. A method to further enhance the thermal conductivity is by the use of a thermal interface material between the device and the heat sink attached to it in the flip-chip technology. Percolation theory holds a key to understanding the behavior of thermal interface materials. Percolation, used widely in electrical engineering, is a physical phenomenon in which the highly conducting particles distributed randomly in the matrix form at least one continuous chain connecting the opposite faces of the matrix. This phenomenon was simulated using the matrix method, to study the effect of different shapes and size of the filler particles. The different shapes considered were spherical, vertical or horizontal rods, and flakes in horizontal or vertical orientation. The effect of the size of these particles was also examined. The results indicate that the composites with particles having the largest side in the direction of heat flow will always have a better conductivity than the particles oriented normal to it. Also, from the results, we can choose the best filler size in the composite if we know the filler concentration we are aiming at.


Author(s):  
ZK Li ◽  
Zhekun Fan ◽  
Long Dou ◽  
Zhong Jin ◽  
Zhan Liu ◽  
...  

Abstract Under the action of electro-thermal-mechanical coupling, the failure and performance degradation of electronic devices are prone to occur, which has become a particularly important reliability problem in microelectronic packaging. The improvement of flip chip reliability by using thermal interface materials was studied. First, a three-dimensional finite element model of the flip-chip packaging system, and finite element simulation of electric-thermal-force multi-field coupling were conducted, and the Joule heating, temperature distribution, thermal stress and deformation of the flip-chip under high current density was analyzed. At the same time, the influence of thermal interface material thermal conductivity and operating current on flip chip reliability was studied. Then, the reliability experiment of the flip chip connected to the radiator under high current density was performed, and the temperature change in the flip chip under different thermal interface materials was obtained. Finally, through the combination of experiment and simulation, the influence of thermal interface materials on flip chip reliability was analyzed. It is further confirmed that the reliability and service life of electronic devices were effectively improved by using the high thermal conductivity BNNS/epoxy composite material prepared in this paper.


Author(s):  
Ankita Verma ◽  
Baqar Tabrez ◽  
Lam Duong ◽  
Martin Wuest

With the increasing demand for thinner packages and higher electrical & thermal performance requirement bare-die packaging is an inevitable trend that is growing. The assembly process for manufacturing of bare die in thin or core-less substrate FCBGA packages can be challenging especially considering the effects of substrate warpage during flip chip bonding and the excessive warpage of the flip chip package. We are evaluating the manufacturing risks during bare-die FCBGA package assembly to eliminate package warpage failures using experimental techniques and improve the functional performance of the flip chip package. Various substrate & under fill materials were tested for package warpage values for warpage-free control in the full range of temperature variation. Die designs at 28nm and 40nm process nodes are extremely complex in order to achieve the highest electrical & thermal performance requirement. Die design constraints on advanced process nodes necessitate increased thermal dissipation requirements thereby requiring investigation of thermal solutions utilizing thermal interface materials (TIM) with heat-sink. The interaction of such thermal solutions with the bare die packages is evaluated using various trial and error for material selection, experimental and simulation techniques to improve the assembly process. This study also focuses on selection of thermal interface materials [TIMs] and heat sinks which have considerable impact on die integrity during package assembly and/or during process of removal for failure analysis.


2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Mathias Ekpu

Purpose In microelectronics industry, the reliability of its components is a major area of concern for engineers. Therefore, it is imperative that such concerns are addressed by using the most reliable materials available. Thermal interface materials (TIMs) are used in electronic devices to bridge the topologies that exists between a heat sink and the flip chip assembly. Therefore, this study aims to investigate the reliability of SAC405 and SAC396 in a microelectronics assembly. Design/methodology/approach In this paper, SnAgCu solder alloys (SAC405 and SAC396) were used as the TIMs. The model, which comprises the chip, TIM and heat sink base, was developed with ANSYS finite element analysis software and simulated under a thermal cycling load of between −40°C and 85°C. Findings The results obtained from this paper were based on the total deformation, stress, strain and fatigue life of the lead-free solder materials. The analyses of the results showed that SAC405 is more reliable than SAC396. This was evident in the fatigue life analysis where it was predicted that it took about 85 days for SAC405 to fail, whereas it took about 13 days for SAC396 to fail. Therefore, SAC405 is recommended as the TIM of choice compared to SAC396 based upon the findings of this investigation. Originality/value This paper is centred on SnAgCu solders used as TIMs. This paper demonstrated that SAC405 is a reliable solder TIM. This can guide manufacturers of electronic products in deciding which SAC solder to apply as TIM during the assembly process.


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