| Multi silicone button pads are widely used in electronic products,but their irregular and large structure requires manual assembly,resulting in low assembly efficiency,high assembly costs and inconvenient maintenance.To address these problems,this dissertation combines SMT to optimise the structure of multi silicone button pads,designs the suction nozzle structure according to the key structure,and uses finite element simulation to research the influence of key structure parameters on the key press performance and assembly performance,and analyses the suction performance of different structure nozzles.The main elements of the dissertation are as follows.（1）A new pin structure in the form of a node is designed to address the problems of the current silicone button pad’s step-pin structure which is inconvenient for assemble automatically and unstable to use.The new structure is more suitable for automatic assembly and more reliable.The effect of the different node structures on the button pad assembly is investigated by finite element simulations.（2）The overall structure of the multi silicone button pad is designed based on the silicone button pad design theory.The button pad with different press structure parameters is simulated and the effect of different parameters on the press performance is investigated.The effect of the different parameters on the pressing performance was investigated.The significance of the effect of each parameter was obtained by extreme difference analysis and analysis of variance,and the pressing structure parameters was optimised.（3）An orthogonal test was designed for the new pin structure to research the effect of different parameters on the button and PCB assembly.The effect of the different parameters and the significance of the influence of each factor were investigated.（4）A new suitable suction nozzle structure has been designed for the new multi silicone button pads.The suction nozzle dimensions were determined by studying the influence of the nozzle suction area on the axial deformation of the button pad.Ten different suction nozzles with different internal flow channel structures were designed and the suction performance and flow field effects of the different suction nozzle structures were investigated by fluid simulation.The results of the study show that:the button pins with arc node structure of the best assembly;the multi silicone buttons are designed in three connected form considering the integration of functional buttons and the size of the buttons required by the automated assembly equipment,the arch structure is used for the button slant wall.The press simulation shows that the elastic slant wall is most easily damaged at the connection with the press tab,the thickness of the elastic slant wall has the greatest influence on the press force,and the initial tilt angle has the greatest influence on the feel of the press.Optimisation of the press structure with a tactile ratio of 59.8%atα=15°,L=0.2317mm and S=2.3148mm.The simulation of the assembly process shows that the maximum interference of the nodes has the greatest influence on the assembly performance of the button,while the influence of the others on the assembly performance is not significant,and the pin structure reference parameters are designed:maximum node excess=0.08mm,pin hole diameter d1=1mm,guide pin diameter d2=1.4mm,node height h=1.2mm.The simulation of the suction nozzle using different positions of the suction surface shows that the influence of the suction surface on the axial deformation of the button at different positions is very small,and considering the minimum influence of positioning and deformation,the suction position is determined to be directly above the pin hole of the button.Then the out shape of the nozzle is determined.For the internal structure of the nozzle,a circular flow channel was chosen for each nozzle hole to connect to the nozzle head,taking into account the results of the fluid simulation and the processing difficulties. |
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