Research On The Key Techniques Of MEMS Thermopile Automatic Die Bonding System

The thermoelectric stack chip based on the MEMS(Micro-Electro-Mechanical System)process has been widely used due to its advantages of small size,high sensitivity,and non-contact temperature measurement.The huge market demand makes it urgent for mass production.At present,the die bonding technology in the manufacture of MEMS thermopile chips all rely on general-purpose die bonding equipment,and the chip is fixed after being modified.This method has a long transformation time and high cost,which cannot meet the actual needs of the enterprise.Therefore,the development of key technologies for special die bonding system with MEMS thermopile die bonding processing technology has important practical significance and research value for reducing the cost in the production process and promoting the development of MEMS thermopile industry.This paper first introduces the temperature measurement principle of MEMS thermopile chip and the process flow of chip packaging.By analyzing the strength requirements of the process,the functional requirements of the die bonding strength on the die bonding system are proposed.On this basis,the requirements for the die bonding gas permeability of thermopile chips are analyzed.Through the simulation of chip die bonding at different temperatures,the optimal die-thickness of the chip was determined to be 40?m,and the functional requirements of the system were proposed.By investigating the influence of precision on the performance of the chip,the fluid state of the MEMS thermopile chip mounted on the silver paste was simulated.The precision of the chip was determined to be 20 ?m,and the accuracy requirement of the die bonding system was proposed.It laid the foundation for the previous process development for the establis.hment of the die bonding system and the construction of the module.Then,the research on the establishment of MEMS thermopile die bonding system was carried out.The die bonding process is described and the functional requirements of the system are summarized.According to the requirements of the system,die bonding system scheme based on linear motor platform was established.On this basis,the motion platform module,dispensing module,chip placement module and system control module were built,which laid the foundation for the MEMS thermopile die bonding control system.In order to meet the requirements of precision for the vision module,the next step is to conduct a visual system study.For the accuracy requirements,the visual module hardware system is designed and built,and the optical components are properly selected.On this basis,the camera internal parameters are calibrated and the MEMS thermopile vision system positioning principle is analyzed.In the process of dispensing,sometimes uneven dispensing and leaking spots may occur.In order to solve this problem,the dispensing quality is pre-determined and then image processed.Then,the design principle of the interface of the die bonding software is determined,and the function of the control software is designed and implemented.Finally,the die bonding experimental study of MEMS thermopile chips was carried out.The experimental analysis of the precision in the process is based on the system platform.The factors affecting the chip's die bonding strength were analyzed and the parameters were optimized.Furthermore,the inner diameter of the needle of ?60?m,the pressure parameter of 0.3Mpa,the dispensing height of 140?m,the patch height of 460?m,and the dispensing time of 1.58s are the optimal eontrol parameters of the process.The experimental test of strength and gas permeability was carried out.The experimental results show that the placement accuracy of the system is higher than 10?m.The die bonding strength based on the process optimization parameters is higher than the minimum shear stress standard of 9.8N.The thickness of the die bonding is also around 40 ?m.This not only satisfies the realization of the automated die-hardening requirements of chips,but also plays a positive role in the mass automated production of MEMS thermopile chips.