超声波振动辅助下填充填缝工艺的数值研究

本文基于数值方法研究了超声波振动辅助倒装芯片成型下填充填缝工艺。采用了一种基于紧耦合的流固耦合算法,对结构和流场之间的耦合运动进行了数值模拟,其中流场部分采用有限体积法对任意拉格朗日-欧拉方法的不可压缩N-S方程进行离散计算,而结构部分采用有限元法对拉格朗日坐标下的弹性动力学方程进行离散计算。在一个时间步内,结构与流场的计算区域的交界面上进行了多次的数值传递和插值,以保证满足耦合面边界条件。计算了超声波振动作为边界条件作用于结构场,而引起的流场中流体流速的变化规律,并通过实验验证了本方法的正确性。同时,监测了流场入口体积流量的变化规律,探究了超声波振幅、频率以及流体粘度等因素对流体流速的影响,为超声波振动辅助倒装芯片成型下填充工艺的应用提供了理论依据。

Numerical study of the ultrasonic vibration assisted underfill process in flip-chip encapsulation

In this paper, a numerical approach was used to study the ultrasonic vibration assisted underfill process in flip-chip encapsulation. The approach, based on a close coupled algorithm, simulated the coupling motion of the fluid and structure. The fluid ,which was modeled by the Arbitrary Lagrangian-Eulerian (ALE) formulation of the incompressible Navier-Strokes equations, was simulated by the finite volume method. The structure was described by the equations of the transient dynamics. In order to couple the interfacial boundary condition, the data transfer and interpolation were performed at the interface of the fluid and structure several times within each time step. As a boundary condition, ultrasonic vibration was exerted on the structure. The velocity of the fluid was calculated accordingly, and was compared with the experimental measurement to verify the proposed approach. And then, the flow rate at the inlet was monitored, and the influence of ultrasonic amplitude, ultrasonic frequency, and the encapsulant viscosity on the fluid flow was studied. The conclusions provide theoretical basis for the application of ultrasonic vibration assisted underfill process.