Study On Bonding Performance Of Silver Alloy Bonding Wires After Passivation Treatment

With the rapid development of microelectronics technology,packaging technology has gradually become an important part of the semiconductor industry from the original semiconductor edge technology.Wire bonding is a traditional packaging interconnection technology,which can realize signal transmission and electrical interconnection between chip and lead frame.Simple process and low cost make its application in electronic components up to 80%.Bonding wires as wire bonding raw material have a variety of forms,gold wire,silver wire and copper wire can adapt to a variety of packaging,but the high price of gold wire,the high hardness,the processing window is small and other shortcomings hinder their application in wire bonding.As a traditional wire bonding material,silver alloy bonding wire has moderate price,good ductility and excellent physical and chemical performance,which solves the problems existing in gold wire and copper wire,and has been widely used in electronic packaging.However,its characteristics of easy vulcanization have not been fully solved,the existing anti-oxidation and anti-sulfurization treatment is to add different contents of gold into the silver alloy bonding wires to improve its anti-discoloration performance,which costs a lot.The method of chemical passivation with high stability and anti-discoloration developed in our laboratory,it solved the problem of silver alloy bonding wires being easy to vulcanize,but the defect of bonding performance after bonded appeared,which hindered the application of silver alloy bonding wires in new fields.In this thesis,the cathodic passivation method was used to creatively add trace Pd ions into the passivation solution.At the same time of chemical passivation,trace Pd was co-deposited in the passivation layer,which can not only significantly improve the anti-vulcanization performance of silver alloy bonding wire,but also maintain the bonding performance of silver alloy bonding wires,and achieve high efficiency and popularization of silver alloy bonding wires in production and application.In order to improve the bonding performance of silver alloy bonding wires,a Pd-containing passivation solution was used to passivate silver alloy bonding wires.Mainly studied the silver alloy bonding wire passivation voltage in the process of passivation and the passivation time for bonding wire surface quality and prevent the respect such as sulfide effect,the effect of simultaneous contrast several conditions after processing of silver alloy wire bonding of reflective performance,mechanical performance and bonding performance,finally,study on the mechanism of these conclusions.The study found that the solution Pd-containing passivating treatment after silver alloy wire bonding processing with the original passivation solution compared with untreated silver alloy bonding wire,prevent sulfide has obvious performance,sulfide gas concentration for 10 g/m~3 environment placed 60 min after silver alloy containing palladium passivation treatment is still present on the bonding surface silver,reflective rate fell by 10%,However,the surface of silver alloy bonded wires treated with original passivation solution and untreated silver alloy bonding wires has changed color,and the reflective rate decreases by 22%and 85%respectively.In terms of bonding performance,the bonding strength of silver alloy bonding wire treated with palladium passivation solution increased from 20.37 gf to 28.02 gf,and the bonding strength increased by 37.5%compared with the shear force of the first solder joint of the silver alloy bonding wires treated with palladium passivation solution.The mechanism of improving the bonding properties of silver alloy bonding wires after passivation with Pd-containing passivation solution was analyzed.It was found that the addition of Pd reduced the surface energy and increased the wettability of the solder balls during the bonding process,thus forming a smaller contact angle,increasing the bonding area and improving the bonding properties.The results of this study can provide a simple method to improve the performance of bonding wires.