基于广义铺展条件下的倒装焊焊点形态预测

Shape prediction of flip chip soldered joints based on generalized spreading condition

随着电子元器引线密度的不断提高,不同条件下焊点形态的精确预测至关重要.考虑钎料量过大溢出到焊盘以外区域(如焊盘外侧的阻焊层或基板)的情况,基于所提出的广义铺展条件建立了适用于倒装焊焊点的三维形态预测模型,给出了基于该模型的能量及体积约束方程.此外,给出了钎料在不润湿表面接触角的测量方法,通过该方法得到了钎料与基板间的润湿角参数,在此基础上利用Surface Evolver有限元软件对倒装焊焊点形态进行了预测并进行了试验验证.结果表明,在各种条件下模拟与试验结果吻合良好.

With increasing requirements of electronic packaging,accurate shape prediction of soldered joints under different conditions becomes critical.When the solder volume is too large,the solder would overflow the pad and spread on other surfaces(e.g.,solder masks around the pad or substrate).Taking this situation into account,a generalized spreading condition was proposed in this paper,and a three-dimensional shape prediction model for flip-chip solder joints was established,and the constrained equations of energy and volume were described.In addition,a novel method to measure contact angles between the solder and non-wetting surfaces such as substrate surfaces was offered.Furthermore,the shape of flip soldered joints was predicted by utilizing a finite element software Surface Evolver,and experimental tests ware performed to verify the simulation results.The simulation results are in good agreement with the experimental results under different conditions.