Research On Low Void Eutectic Technology Based On High Power Chip

In the era of rapid development of semiconductor technology,with the development of semiconductor chips towards the direction of high power,small size and high integration,higher requirements are put forward for heat dissipation technology in high-power chip packaging.Eutectic soldering technology is the main method of high power chip packaging.The void rate of eutectic joint will directly affect its thermal resistance,which will affect the junction temperature of the chip,and finally affect the service life of the chip.Therefore,low-void and no-void eutectic technology is widely favored by the industry,but it needs to purchase highend packaging equipment in Europe and the United States,the cost is high,and the equipment control software cannot realize the automatic integration of multiple process parameters.In this thesis,the void rate regression model is studied for high-power chips,and implanted into the vacuum eutectic soldering system studied in this thesis.The low void eutectic soldering with independent optimization of multiple process parameters is realized.The main work of this thesis is as follows:Firstly,the theoretical basis of eutectic technology and the key parameters affecting the void rate are studied.According to the design requirements of chip eutectic soldering,innovative eutectic soldering fixture was designed to realize high precision positioning in the process of power chip soldering and avoid chip shift.According to the characteristics of the solder material,the gold-tin solder was optimized,and the solder was processed into preformed solder according to the actual soldering condition,which eliminated the influence of the auxiliary technology of eutectic soldering on the void rate.Without considering the quality of experimental materials,the main process parameters affecting the void rate of eutectic joint were determined as follows: soldering temperature,soldering time and soldering pressure.Next,the vacuum eutectic soldering system is studied.In the aspect of system hardware,the heating module of vacuum eutectic soldering equipment was designed and optimized,which improved the temperature uniformity and heating efficiency in the furnace.And the hardware circuit design,STM32F103ZET6 as the controller,the power module,temperature measuring module,pressure measuring module,temperature module and cooling module control.In the aspect of system software,each module is programmed to realize the control of temperature and pressure in the furnace;And using OLED screen and mouse as the carrier of data display and instruction transmission,to achieve good human-computer interaction function.Then,according to the main process parameters affecting the void rate of eutectic joint,the void rate regression model of high-power chip was established for the first time.The orthogonal test method and multivariate nonlinear regression method were used to combine the void rate of chip as the evaluation index,and the void rate regression model was implanted into the vacuum eutectic soldering system through programming,realizing the independent optimization of multiple process parameters.Finally,the vacuum eutectic soldering system implanted with the void rate regression model is verified by experiments.The void rate of high-power chip is lower than 5% after using the system,which is much lower than the 25% requirement stipulated by the national standard GJB548B-2005.The purpose of low-void eutectic soldering of high-power chip is realized.In conclusion,the vacuum eutectic soldering system implanted with void rate regression model in this thesis achieves low void rate eutectic soldering of high-power chips,meets the packaging requirements of high-power chips,and greatly reduces the cost,laying a technical foundation for the wide application of high-power chips.