Research On Conductive Bonding Technology And Reliability Of Flexible Solar Cell Array

As a lightweight,high-efficiency,small-volume photovoltaic module,flexible solar cells are the main research direction of the future aerospace industry,and the promotion of flexible solar cells is based on the new flexible solar array interconnection technology.At present,the main solar cell array interconnection technologies have their own shortcomings and are not suitable for use in the field of flexible solar cells.Therefore,there is an urgent need to develop a flexible,excellent conductivity,high reliability solar cell array interconnection technology.With its unique advantages,conductive adhesive interconnection technology has become a new interconnection process in the field of microelectronics and packaging in recent years.In this paper,the conductive adhesive interconnection technology is applied to the preparation of the conductive adhesive joint of solar cells by taking advantage of the excellent conductive and mechanical properties of the conductive adhesive,so as to explore the feasibility of the conductive adhesive joint of solar cells.In this paper,a conductive adhesive with unique mechanical and electrical properties is prepared by formula design and mixed grinding of resin matrix,micron silver powder,Ga In Sn liquid alloy,Sn Bi alloy.The curing process of conductive adhesive was explored,and the change of resistance value during the curing process of conductive adhesive was monitored.The curing temperature of 160 °C and the curing time of 35 min were determined as the appropriate curing process parameters of conductive adhesive.The conductive adhesives with different conductive filler contents were micro-characterized and compared with their properties,and it was determined that the appropriate addition amount of conductive filler was 70 wt%.The solar cell adhesive joint was prepared by using conductive adhesive,and the cross-sectional morphology of the joint was microscopically characterized.Based on this,two low melting point alloy mixed silver powders were designed to prepare a composite conductive adhesive.The study found that under the same mass fraction of conductive fillers,the increase in the content of the Ga In Sn liquid alloy will gradually reduce the conductivity of the conductive adhesive without pressure curing,and through microscopic characterization,it is found that the doping of the liquid alloy will improve the probability of generating voids and holes in the interior of the conductive adhesive,and the application of curing pressure will greatly increase the possibility of internal cracks in the composite conductive adhesive.For the composite conductive adhesive doped with low-melting Sn Bi alloy,the study found that the curing temperature has a great influence on the conductivity of the Sn Bi alloy composite conductive adhesive,and when the curing temperature is low,the Sn Bi alloy does not melt in the conductive adhesive,and when the solidification temperature is high,the Sn Bi alloy melts and forms a river-like conductive network.Using COMSOL Multiphysics to simulate the joint model,it is explored that the thermal fatigue danger zone of the joint is located at the corner of the conductive adhesive.The conductive filler particle model is introduced to obtain the joint dangerous point coordinates and simplify the joint model.Through thermal fatigue simulation analysis,the temperature field,stress field and equivalent plastic strain field distribution of the micro joints containing silver flakes and silver particles are obtained.The dangerous point of the micro-conductive adhesive joint is calculated,and the hysteresis curve and strain curve at the dangerous point are obtained,and the fatigue life of the joint is calculated.