Preparation Of Low Temperature Sintered Silver Paste And Its Application Research On Tempered Glass Joining

As a glass product with good sound insulation and heat insulation effect,vacuum glass is widely used in buildings,doors,windows,incubators and airtight seals.It is the key development direction of energy-saving and environmentallyfriendly glass products in the future.Due to the high strength of tempered glass and use security,it has become a research focus of vacuum glass products by replacing ordinary glass to manufacture safe vacuum glass.This paper aims to prepare a silver paste that can be sintered at a low temperature and can ensure the tempering performance of the glass substrate and have high adhesion strength after sealing.Further using it to seal vacuum tempered glass,the seals can meet the requirements of ensuring air tightness and safety in use.In this paper,a low-melting glass frit?glass transition temperature of 354 ?,crystallization temperature of 453 ??has been successfully prepared and tested after being formulated into a glass paste.By studying the sealing performance of the glass paste,the defects of glass paste sealing are found,which leads to the feasibility of subsequent silver paste sealing.The microstructure of the sintered silver film is analyzed in depth.The silver film contains silver,glass phase,and Bi₄B₂O₉ crystals precipitated from the glass phase.During the sintering of the silver film,the molten glass frit penetrates into the gaps of the silver particles by capillary force to fill it.At the same time,it spreads on the surface of the glass substrate.So the sintered silver particles are tightly combined with the glass substrate and play a bonding role.There is a 40 nm diffusion layer at the interface between the silver film and the glass substrate.The precipitation of finely dispersed Bi₄B₂O₉ nanocrystal grains plays a strengthening role.The dissolution and precipitation process of silver micron particles in the glass frit accelerates the diffusion and transfer of elements,promotes the sintering and growth of the mixed particles.And the brittle frit skeleton matched with the high soft plasticity of silver to obtain a high-density,good-performance silver film sintered structure.After the silver paste was sealed,the seals are tested for shear strength.It is found that the silver balls were peeled off,leaving a bowl-shaped glass structure on the glass substrate.This structure can greatly increase the contact area between the glass substrate and the silver film.The presence of silver hinders the expansion of cracks in the frit,causing the expansion of cracks needs to go around the surface of the silver ball.The effects of sintering process,glass frit content and silver particlesize on the microstructure and shear strength of silver film were investigated.The interface and shear fracture behavior were analyzed and the variation rules were summarized.Finally,the vacuum tempered glass was prepared by designing the vacuum sealing structure.The seals prepared with 1 ?m silver powder,80 wt.%silver,20 wt.% glass frit content and under sintering process at 450 ? for 10 min combined with soldering exhibit excellent performance.On the premise of ensuring the properties of tempered glass,the shear strength of seals is 42.3 MPa and the leakage rate is 7.2×10^-3 Pa.cm³ s.Finally,the heat transfer test proves that the vacuum tempered glass prepared by the method of this paper has excellent thermal insulation performance.