氮化铝陶瓷的椭圆超声辅助固结磨粒抛光研究

Elliptic Ultrasonic Assisted Fixed-Abrasive Polishing of AlN Ceramics

氮化铝陶瓷因其良好的导热性、与硅接近的热膨胀系数和优异的机械强度等优点,作为高集成度和高功率器件封装最理想的载板材料而广受关注,在航空航天、汽车、芯片和国防军工中有着良好的应用前景。目前使用最广泛的氮化铝陶瓷载板平坦化方法主要是研磨和抛光,然而其游离磨粒的特性导致了材料去除率偏低,加工效率遭遇瓶颈,此外,其磨浆中的化学物质也会造成环境成本的提高。为了进一步提高氮化铝陶瓷的抛光效率,解决环境不友好问题,首先采用陶瓷结合剂固结磨粒磨具开展氮化铝陶瓷的干式固结磨粒抛光试验,结果表明,固结磨粒抛光可以获得更高的材料去除率,但排屑困难会导致表面完整性的恶化。针对这一情况,随后采用了在干式抛光过程中对磨具施加椭圆超声振动的方法,试验结果证明椭圆超声振动对排屑有促进作用,有利于提高抛光质量和材料去除效率。

AlN ceramics are considered as the most ideal substrate material for high integration and highpower devices packaging due to its high thermal conductivity,low thermal expansion coefficient and good mechanical strength,and have great prospects for application in automotive chips,aerospace and defense military.However,as the primary methods of the substrate planarization,lapping and polishing of AlN ceramics are encountering the bottleneck of low processing efficiency caused by the employment of loose abrasive slurries.In addition,the chemicals in abrasive slurries can cause increased environmental expenses.In this research,for the purpose of solving environmental problems and improving the polishing efficiency of AlN ceramics,a vitrified-bonded abrasive pellet containing fine abrasives is employed to realize the fixed-abrasive dry polishing.With this method,higher material removal rate can be obtained,but the chip cannot be discharged in time during the dry machining,which will lead to the deterioration of surface integrity.Consequently,an elliptic ultrasonic vibration is applied to the abrasive pellet during the dry polishing.It is found from experiments that the elliptic ultrasonic vibration has a catalytic effect on the chip emission,which is more favourable for better surface quality and higher material removal rate.