Device And Technology For High-viscosity Liquid Micro-dispensing

Micro bonding technology is widely used in the bonding and packaging of tiny parts.In order to ensure the bonding strength,high-viscosity liquid is often used to bond tiny parts.The micro-dispensing of high-viscosity liquid has a significant effect on the connection performance of microdevices.It is urgent to develop a reliable micro-dispensing technology for high-viscosity liquid.Due to the limitation of high viscosity resistance,the amount of high-viscosity liquid can not meet the actual demand when it is dispensed by injection.Adhesion and transfer pressure exist between the transfer head,the liquid and the substrate surface,which are important for the transfer dispensing method of the liquid.This method eliminates the restriction of the flow resistance in the tube.It is suitable for the micro-dispensing of high-viscosity liquid.The transfer dispensing method consists of adhesive loading and adhesive transferring steps.Different volumes of adhesive can be transferred by changing the pressure.However,a suitable way to loading adhesive has not been found.The electric field force is the dominant surface force at the micro scale.Inspired,the electric field force can be applied to adhesive loading.In this paper,a adhesive micro-dispensing system based on electrostatic induced loading and force feedback transfer of adhesive is developed.The micro-dispensing technology of high-viscosity liquid is studied experimentally with the system.Firstly,the simulation of electrostatic induced loading adhesive is established.The influences of the initial height of transfer head from adhesive surface,current etc.on droplet-loading and transferring process of adhesive are analyzed and evaluated.By establishing the simulation of double transfer head loading adhesive,the rheological state of adhesive when double transfer head loading adhesive are calculated and analyzed.According to the results of finite element calculation,the technical indexes of dispensing process are determined.Secondly,the structure of each module of the micro-dispensing prototype is designed.The prototype mainly includes precision positioning module,micro adhesive shifting module and shelf for materials module.The precision positioning module and the micro adhesive shifting module constitute the actuator of the prototype,which is used to complete the adhesive loading and transferring operation.The shelf for materials module is used to place the gold-plated silicon wafer coated with adhesive and parts.In order to control the prototype,network port and serial port are used to realize the connection and communication between IPC and each unit module.After that,the software control process is designed according to the operation steps of adhesive micro-dispensing.The software control process mainly includes several parts.They are the measurement of adhesive thickness,droplet loading by electrostatic induction,visual selection of the transfer position and droplet transferring by force feedback.According to the control process,the program is modularized programming.Then the four modules of system management,laser scanning,adhesive loading and adhesive transfer are integrated into a complete system software.The human-computer interaction interface of the software is designed reasonably,which is convenient for users to operate.At last,the adhesive micro-dispensing system is used to carry out the epoxy resin adhesive dispensing experiment.Using a single transfer head to carry out adhesive dispensing experiment.By adjusting the initial height of the transfer head from the adhesive surface and the current threshold,0.43 n L? 2.81 n L epoxy resin adhesive transfer is completed.Using a double transfer head to carry out adhesive dispensing experiment.The influence of uneven adhesive film thickness on the process of double transfer head adhesive loading is studied and analyzed.