| Three-dimensional integrated packaging plays an increasingly important role in the field of electronic packaging.In the process steps of three-dimensional integrated packaging,bonding technology is one of the key processes.How to connect the substrates to each other at a lower temperature,maintain firm bonding,and achieve insulation or conduction of the bonding layer according to requirements has become one of the key issues in three-dimensional integration.As a commonly used wire bonding material,goldtin alloy has been widely used in electronic packaging.It has the characteristics of low bonding temperature,high bonding strength,and good airtightness.In the insulation medium bonding,it is mainly used as a representative of organic polymers,benzocyclobutene(BCB),as a new generation of electronic packaging adhesive,has low curing temperature,low moisture absorption,high adhesion,stable low dielectric and low loss,and is used in three-dimensional integrated packaging.The field has a wide range of application prospects.The traditional main means to reduce the bonding temperature are to improve surface activity and reduce impurity pollution by means of ultraviolet rays,plasma,and high vacuum.The above method is not suitable for production due to high cost and cumbersome steps,and demanding conditions.In this context,this paper studies two bonding process methods suitable for glass substrate bonding with low bonding temperature,high bonding strength,and tolerance to the bonding environment.It provides bonding technology support for the integration of the three-dimensional system on the glass substrate.The main work content of this paper includes the following aspects:(1)The effect of temperature and pressure on the bonding result during the bonding process of gold-tin alloy is studied.After the phase transition point of the gold-tin alloy is exceeded,only a pressure of 0.6 Mpa can be applied to form a bond.The bonding strength after bonding was 3.41 MPa.(2)Compared with the bonded sample with gold-tin alloy on both sides,the sample with gold and gold-tin alloy as the bonding medium on the bonding surface has higher bonding strength.Some documents show that gold atoms have better diffusion properties,and a more uniform bonding layer can be obtained under the same bonding conditions.Under the same temperature and bonding pressure(283 °C,0.6 MPa),gold and gold The bonding strength of tin alloy is 4.91 MPa.(3)The relationship between the BCB spin rate and the thickness of the bonding layer was studied.In the BCB glue pre-bonding process,the degree of drying after the glue is strongly related to the integrity of the bonding interface.Insufficient drying after the glue will cause the subsequent heating and curing steps to fail to gather in the bonding interface.The discharged organic solvent reduces the effective bonding area and adversely affects the bonding strength.Under curing conditions of 250 °C,the highest bonding strength of the BCB bonded sheet is 4.27 MPa.(4)In the curing and bonding step,the degree of polymerization of the BCB glue is the main factor that determines the bonding strength.Under the same curing time of 1hour,the bonding interface of the sample with a curing temperature of 250℃ is the most complete Even if the temperature is too low or too high,small bubbles will accumulate inside.When the curing temperature is less than 250 °C,the same bonding effect can be achieved by increasing the curing time.When the bonding temperature is 200 °C,the internal air bubbles gradually disappear with the extension of the curing time.Under the curing condition of 200 °C,the highest bonding strength of the BCB bonded sheet is 3.37 MPa. |
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