Preparation And Properties Of Silicone-based Electrically Conductive Adhesive Applied In Shingled Photovoltaic Module

With the rapid development of the new shingled photovoltaic module technology,the silicone-based electrically conductive adhesive plays an important role in the power generation efficiency and service life of photovoltaic module as a kind of green bonding material.The silicone-based electrically conductive adhesive has the advantages of mild curing temperature,high production efficiency and environmental friendliness.However,the adaptability of the silicone-based electrically conductive adhesive to spray process,the stability of volume resistivity and adhe sion force of the silicone-based electrically conductive adhesive have a great influence on its practical application.Therefore,it is of great significance to study the electrical properties,adhesive properties and technological properties of the silicone-based electrically conductive adhesive in shingled photovoltaic module.In this paper,firstly,the base adhesive of the silicone-based electrically conductive adhesive was prepared,then the silicone-based electrically conductive adhesive was prepared using silver powder as conductive filler,and the electrical properties,adhesive properties and technological properties were studied.（1）The viscosity and storage time of the base adhesive of the silicone-based electrically conductive adhesive samples were studied by changing the ratio of catalyst and inhibitor under different temperature conditions.The results show ed that the viscosity of the base adhesive of the silicone-based electrically conductive adhesive increased 25%after 7 months storage at-15℃,and it took 48 hours for the viscosity to increase 25%at room temperature when the mass ratio of catalyst and inhibitor was2:1.After 200 h and 500 h hot oxygen aging,the tensile strength of the base adhesive sample was basically unchanged,and the elongation at break gradually decreased and the hardness increased with the increase of aging time.（2）The silicone-based electrically conductive adhesive was prepared using silver powder as conductive filler.The influence of conductive filler and curing process on the electrical and mechanical properties of the silicone-based electrically conductive adhesive were studied.The results showed that the volume resistivity of the silicone-based electrically conductive adhesive decreased with the increase of silver powder size,and the volume resistivity of the silicone-based electrically conductive adhesive prepared by flake silver powder was significantly smaller than that the spherical silver powder.The volume resistivity of the silicone-based electrically conductive adhesive decreased with the increase of curing temperatureand curing time.The shear strength of the silicone-based electrically conductive adhesive increased with the increase o f curing temperature and curing time.The volume resistivity and the shear strength of the silicone-based electrically conductive adhesive were 8.0*10^-4Ω·cm and 2.2 MPa respectively at the curing condition of 160℃and 30 min.（3）The effects of spray parameters on the size and morphology of the silicone-based electrically conductive adhesive,as well as the effects of viscosity and thixotropic index of the silicone-based electrically conductive adhesive on spray performance were studied.The results showed that the diameter of the silicone-based electrically conductive adhesive points and the distance between the points increased with the increase of the opening time of the spray valve.When the feeding air pressure increased,the height of adhesive point became low,the diameter of adhesive point and the unit consumption increased.With the decrease of the stroke of the striker,the diameter of the adhesive point sprayed out become smaller and the height of the adhesive point increased.The viscosity and the height of spray point of the silicone-based electrically conductive adhesive prepared using flake silver powder as conductive filler was greater and higher than that of spherical silver powder,and the appearance was not round enough.The thixotropic index of the silicone-based electrically conductive adhesive prepared using spherical silver powder was lower than that of flake silver powder.With the increase o f silica content,the thixotropic of the silicone-based electrically conductive adhesive increased.The thixotropic index of the silicone-based electrically conductive adhesive was 4.7 at the silica content of 3 wt%.The silicone-based electrically conductive adhesive with larger thixotropic index had stronger plasticity and fuller appearance.After laminating,the silicone-based electrically conductive adhesive with larger thixotropic index had smaller adhesive point diameter,which could reduce the overflow phenomenon.