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首页> 外文会议>International Welding/Joining Conference-Korea; 20070510-12; Seoul(KR) >Effect of Laser Parameter on the Bond Characteristics of Sn-3.5Ag Solder Ball
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Effect of Laser Parameter on the Bond Characteristics of Sn-3.5Ag Solder Ball

机译：激光参数对Sn-3.5％Ag焊球结合特性的影响

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Pulsed Nd;YAG laser was applied to investigate the bond characteristics of Sn-3.5wt%Ag (hereafter, Sn-3.5Ag) solder ball. The ball diameter is 500μm, and the UBM (Under Bump Metallurgy) on a FR4-PCB consisted of Cu/Ni/Au from bottom to top with thickness of 50μm/25μm/0.05μm, respectively. A RMA (rosin mildly activated) flux for BGA (Ball Grid Array) was applied before laser soldering to set up the solder ball on the UBM. Laser power was 250W, and its beam diameter at the focal point was around 250μm. Experimental results reveal that the solder ball showed a good bonded state when the laser energy was in the range between 0.8 and 1.0 J. Laser energy lower than 0.8J caused non-wetting of the solder ball, and energy higher than 1.2J showed crack along the UBM. Microstructure of the laser soldered Sn-3.5Ag was examined with the number of pulse, when the frequency, pulse width and laser energy were fixed at 5 Hz. 20 ms and 0.8 J, respectively. The IMC (Intermetallic Compound) of Ag_3Sn in the solder changed from acicular to rod type with increasing laser pulses. Ni_3Sn_4 was produced between the solder and the UBM, and its thickness increased from 0.65 to 1.80μm with increasing number of pulse from 2 to 4. These are thinner than those of general air reflow. Shear strength of the laser soldered ball with output energy of 1 J showed 652.3 gf, and it was similar value compared to the result from hot plate soldering, 654.5 gf.
机译：用脉冲Nd; YAG激光研究了Sn-3.5wt％Ag（以下简称Sn-3.5Ag）焊球的结合特性。球直径为500μm，FR4-PCB上的UBM（凸块下冶金）由下至上分别由Cu / Ni / Au组成，厚度分别为50μm/25μm/0.05μm。在进行激光焊接之前，先为BGA（球栅阵列）施加RMA（轻度活化的松香）助焊剂，以在UBM上设置焊球。激光功率为250W，焦点处的光束直径约为250μm。实验结果表明，当激光能量在0.8至1.0 J之间时，焊球呈现出良好的结合状态。低于0.8J的激光能量导致焊球不润湿，而高于1.2J的能量则沿焊缝出现裂纹。 UBM。当频率，脉冲宽度和激光能量固定在5 Hz时，用脉冲数检查了Sn-3.5Ag激光焊接的显微组织。分别为20 ms和0.8J。随着激光脉冲的增加，焊料中Ag_3Sn的IMC（金属间化合物）从针状变为棒状。 Ni_3Sn_4是在焊料和UBM之间产生的，其厚度从0.65增加到1.80μm，脉冲数从2增加到4。这些厚度比普通空气回流焊的厚度薄。输出能量为1 J的激光焊接球的剪切强度为652.3 gf，与热板焊接的结果654.5 gf相似。

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