Abstract. During the process of warm water isostatic pressing process, the internal micro-channels fabricated in Low Temperature Co-fired Ceramic (LTCC) substrate are prone to collapse. In this paper, a three-dimensional model of LTCC microwave component is established by the finite element software ABAQUS, and the micro-channel deformation is studied by the simulation analysis of warm water isostatic pressing process. Results show that pressure is the main factor that leads to the deformation of micro-channel, and temperature is followed. At the same time, the microchannel with large width-height ratio-aspect ratio has large deformation. Choose smaller pressure 18 MPa and high temperature 80 ℃, microchannel deformation can be controlled below 15%.
Based on the minimal energy principle, the shape prediction models of the 0 . 5 mm pitch, 16 pin quad flat no lead (QFN) package solder joints were developed. The influence of the process parameters including the pad length, the pad width and the stand-off on the solder joint shape of QFN was studied. Utilising the surface coordinate exported from the QFN solder joint shape prediction models, finite element analysis (FEA) models were set up and then the non-linear FEA of the QFN solder joints under thermal cycles was performed by ANSYS. The stress-strain distribution within the solder joints and the maximum strain range of the solder joint were determined. The thermal fatigue life of the QFN solder joint was calculated based on the maximum strain range and the Coffin-Manson equation. The results show that the process parameters influence the QFN solder joint shape distinctly, and the QFN solder joint with different pad lengths, pad widths and stand-offs has various stress-strain distributions and fatigue life. The QFN solder joint with a pad length of 0 . 7 mm, a pad width of 0 . 28 mm and a stand-off of 0 . 125 has a fatigue life of 252 cycles under thermal cycles.
After Au80/Sn20 eutectic soldering GaAs chips process, Au80/Sn20 solder joints will have large residual stress and strain because of materials' coefficient of thermal expansion (CTE) mismatch. Large strain deformation will lead to the chip position migration. On the other hand too much stress can make the interface micro cracks and affect the quality and long-term reliability of Au80/Sn20 solder joints. Choosing welding pressure, cooling rate and the thickness of the precast solder pieces as the key process parameters, and designing the L16 (43) orthogonal test table. According to the Au80 / Sn20 eutectic soldering real environment, using finite element analysis software ANSYS to establish the simulation model of Au80 / Sn20 eutectic soldering process. After simulation analysis, it got the maximum residual stress and the strain energy of the solder joint. The primary of the factors is cooling rate, the secondary of the factors is the thickness of the precast solder pieces and pressure is the last by range analysis. The achieved process parameters and forming residual stress and the strain energy of the relationship between solder joints can provide reference and guidance for practical production. Eutectic welding processAu80/Sn20 eutectic welding technology is a low melting point technology. Under the temperature (280℃), solder Au80/Sn20 appears eutectic fusion phenomenon, the alloy directly International Conference on Information Sciences, Machinery, Materials and Energy (ICISMME 2015)
The vacuum eutectic solder joint is widely used in the advantages of large thermal conductivity, small thermal resistance and so on. But the void ratio of vacuum eutectic solder has a great influence on the thermal conductivity, and the smaller the void ratio is, the greater the thermal conductivity coefficient is. Therefore, it is very necessary to optimize the parameters of vacuum eutectic welding process and reduce the void ratio of solder joints. In this paper, the three-dimensional finite element simulation model of the welding of the GaAs chip and the heat sink is established by using ANSYS software. The peak temperature, cooling rate and pressure as the main welding parameters of vacuum eutectic solder joint were selected as the main welding parameters[1]. In the method of keeping the two parameters unchanged for another parameter of the change, such as changing the cooling rate and the other parameters remain unchanged for simulation, similar to change pressure and peak temperature simulation and analysis of process parameters on the solder joint void rate effect rule, get the smallest solder joint void rate combination of process parameters. The research shows that the cooling rate has the most significant effect on the void of vacuum eutectic solder joint. In the range of 1.5℃/s ~2℃/s, with the increase of cooling rate, the void ratio increases, the maximum is 8.148% at 1.6℃/s, and then remains stable. The peak temperature is less important. On the simulation of the void rate of parabolic law, in the peak temperature range of 300℃~310℃, with the increase of the peak temperature, the simulation after the void first increases and then decreases, at 307℃ to 8.148%. The effect of pressure is the smallest, with the increase of pressure, the void ratio remains unchanged after simulation. According to the analysis of the process parameters of the simulation, the vacuum co crystal welding solder joint void rate minimum combination of process parameters: peak temperature is 307℃, the cooling rate is 1.5℃/s, the pressure is 400~2000Pa.
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