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首页> 外文会议>2002 ASME International Mechanical Engineering Congress and Exposition , Nov 17-22, 2002, New Orleans, Louisiana >MARANGONI AND VARIABLE VISCOSITY PHENOMENA IN PICOLITER SIZE SOLDER DROPLET DEPOSITION
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MARANGONI AND VARIABLE VISCOSITY PHENOMENA IN PICOLITER SIZE SOLDER DROPLET DEPOSITION

机译：胶粒大小的锡珠沉积中的Marangoni和可变粘度现象

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摘要

This numerical investigation studied the effects which the temperature dependence of surface tension (Marangoni phenomenon) and viscosity has on the spreading, the transient behavior and final post-solidification shape of a molten Sn63Pb solder droplet deposited on a flat substrate. A Lagrangian finite element formulation of the complete axisymmetric Navier-Stokes equations was utilized for the description of the droplet behavior. Linear temperature dependence for the surface tension and an exponential dependence for the viscosity were assumed. The initial droplet temperature was varied in 50K steps from 200℃ to 500℃, whereas the substrate temperature was kept constant at 25℃. This varied the initial Reynolds number Re_0 from 360 to 716 and the Marangoni number Ma from -9 to -49. The initial Weber number We_0 and initial Prandtl number Pr_0 were for all cases O(1) and O(10~(-2)), respectively. The impact velocity and the droplet diameter remained unchanged in all cases examined at 1.5 m/s and 80 microns. A major finding of the work was that, contrary to intuition, the Marangoni effect decreased droplet spreading monotonically. Due to the Marangoni effect, surface tension forces instead of freezing arrested spreading. Droplet receding during recoiling was aided by the Marangoni effect. On the other hand, the change of viscosity with temperature showed no significant influence on the outcome of the droplet impact.
机译：该数值研究研究了表面张力（Marangoni现象）和粘度的温度依赖性对沉积在平坦基板上的熔融Sn63Pb焊料滴的扩散，瞬态行为和最终的凝固后形状的影响。完整的轴对称Navier-Stokes方程的拉格朗日有限元公式用于描述液滴的行为。假定表面张力的线性温度依赖性和粘度的指数依赖性。初始液滴温度从200℃到500℃以50K的步长变化，而基板温度保持恒定在25℃。这将初始雷诺数Re_0从360更改为716，将马兰戈尼数Ma从-9更改为-49。在所有情况下，初始韦伯数We_0和初始普朗特数Pr_0分别为O（1）和O（10〜（-2））。在所有情况下，在1.5 m / s和80微米的条件下，冲击速度和液滴直径均保持不变。这项工作的主要发现是，与直觉相反，Marangoni效应减少了单调扩散的液滴。由于Marangoni效应，表面张力而不是冻结阻止了扩散。在回卷过程中，Marangoni效应有助于液滴后退。另一方面，粘度随温度的变化对液滴冲击的结果没有显着影响。

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