Research On Self-assembly Technology Of Microchips Based On Surface Tension

With the rapid development of micro-electro-mechanical system(MEMS)and the design and manufacturing technology of micro-devices,the innovative research and development of electronic equipment has attracted much attention.At present,the widely used electronic equipment tends to develop in the direction of large-scale multi-functional integration,miniaturization and flexibility.Under this trend,chips are required to continue to tend to micron scale,but the manipulation of microchips at microscale is affected by a variety of adhesion forces,which makes it difficult to achieve controllable manipulation.The key to the manufacture of new electronic devices is the large-scale and efficient integration of multi-functional microchips on the substrate.Traditional microchip integration technology can not meet need for manufacturing new electronic devices.Therefore,the efficient and high-precision assembly of microchip is an urgent problem to be solved in the integration of electronic equipment.In the thesis,a micro-chip self-assembly technology based on surface tension is proposed,which combines robot pick-and-place technology with the surface tension based self-alignment technology,and makes use of the flexibility of robotic pick-and-place technology and efficiency of self-alignment technology.At the same time,surface tension plays a dominant role in micro-scale,which can overcome other adhesion forces to achieve effective and controllable micromanipulation.In addition,liquid droplets are confined to designated positions on the substrate.The technology realizes high-precision positioning and assembly of microchip on the substrate.This thesis studies the subject from four aspects: theoretical analysis,numerical simulation,experimental platform construction and experimental analysis.(1)Based on the theory of surface tension and energy minimization,the theoretical models of two kinds of misalignment modes in self-assembly process are established.The relationship between the dislocation displacement and the surface energy of the liquid bridge,The relationship between the misalignment and the restoring force(torque)of the liquid bridge on the micro-chip under different droplet amounts is analyzed.It is theoretically proved that the selfalignment process of the micro-chip follows the principle of energy minimization.The self-assembly system is in the minimum energy state after self-alignment.(2)The numerical simulation model of micro-chip self-assembly system is established using Surface Evolver software.The shape of liquid bridge and the free energy of the system under two kinds of misalignment modes are solved.The relationship between the misalignment and the surface free energy of the liquid bridge is analyzed,the relationship between the misalignment and the restoring force(torque)of the microchip is also analyzed.In addition,the influence of the substrate and the micro-chip contact angle on the self-assembly of micro-chip is obtained.(3)Combining with the operation flow of microchip self-assembly,the overall construction scheme of the self-assembly experimental platform and the reasonable control scheme of data acquisition and signal transmission are designed.An experimental platform is setup which consists of motorized stages with nanometer precision,piezoelectric microgripper,precision injection pump and vision system,and the various parts of the experimental platform are embedded,controlled and debugged based on Automation Base software.The overall control of the experimental platform is completed,and the corresponding self-assembly control program is compiled.(4)In order to achieve micro-chip self-assembly,firstly,the influence of laser processing parameters on droplet restriction was studied.Then,self-assembly tests of microchips with different sizes under different droplet volumes were carried out on the experimental platform,and the effects of liquid volume on the success rate and duration of self-assembly of microchips were analyzed.The effects of the displacement error between microchips and substrates on the success rate of selfassembly of microchips were obtained.In addition,self-assembly tests of rectangular and circular microchips were carried out,which laid the foundation for the promotion of surface tension self-assembly technology in the field of electronics.