Effects of Pd(P) Thickness on the Microstructural Evolution Between Sn-3Ag-0.5Cu and Ni(P)/Pd(P)/Au Surface Finish During the Reflow Process
Effects of Pd(P) Thickness on the Microstructural Evolution Between Sn-3Ag-0.5Cu and Ni(P)/Pd(P)/Au Surface Finish During the Reflow Process
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DOI：
10.1007/s11664-012-2320-2
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发表时间：
2012-11
影响因子：
2.1
通讯作者：
B. Chung;Y. Baek;Jaeho Choi;J. Huh
中科院分区：
文献类型：
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作者：
B. Chung;Y. Baek;Jaeho Choi;J. Huh
研究了不同Pd(P)厚度(0μm~0.6μm)条件下，Sn3Ag-0.5Cu(SAC30 5)焊料与Ni(P)/Pd(P)/Au焊料在回流焊过程中的组织演变。回流焊在峰值温度为260℃的带式回流焊炉中进行。在回流焊初期，Pd(P)层以(Pd，Ni)Sn4的形式溶解或剥落到熔体中，在Ni(P)层上形成Ni2SnP/Ni3P双层膜。从回流过程中剥落的(Pd，Ni)Sn4颗粒的溶解情况估计，Pd在回流过程中在SAC305熔体中的溶解度为0.18~0.25wt.%。无论焊料体积与焊盘开孔尺寸之比如何，在回流初期形成的Ni2SnP层对随后在焊料界面形成和生长(Cu，Ni)6Sn5有显著影响。随着Pd(P)厚度的增加，Ni2SnP层变厚，(Cu，Ni)6Sn5的形成变得越来越缓慢，并且只发生在Ni2SnP层局部较薄或不连续的地方，导致(Cu，Ni)6Sn5的不连续形态。这是由于随着厚度的增加，Ni2SnP层逐渐成为镍扩散的有效阻挡层。基于实验结果，本研究提出了Pd(P)厚度对回流过程中形成的(Cu，Ni)6Sn5相的形态和生长的影响的详细机制。
The microstructural evolution between Sn-3Ag-0.5Cu (SAC305) solder and Ni(P)/Pd(P)/Au finish during the reflow process was investigated for various Pd(P) thicknesses (0μm to 0.6μm). The reflow process was carried out in a belt-conveying reflow oven with peak temperature of 260°C. In the early stages of the reflow process, the Pd(P) layer either dissolved or spalled in the form of (Pd,Ni)Sn4into the molten solder, leaving behind an Ni2SnP/Ni3P bilayer on the Ni(P) layer. From the dissolution of the spalled (Pd,Ni)Sn4particles during the reflow process, the solubility of Pd in the molten SAC305 solder in the reflow process was estimated to be 0.18 wt.% to 0.25 wt.%. Regardless of the ratio of solder volume to pad opening size, the Ni2SnP layer that formed in the early stage of reflow had a significant influence on the subsequent formation and growth of (Cu,Ni)6Sn5at the solder interface. As the Ni2SnP layer became thicker with increasing Pd(P) thickness, the formation of (Cu,Ni)6Sn5became increasingly sluggish and occurred only at locations where the Ni2SnP layer was locally thin or discontinuous, leading to a discontinuous morphology of (Cu,Ni)6Sn5. This was attributed to the Ni2SnP layer that became an increasingly effective barrier to Ni diffusion with increasing thickness. Based on the experimental results, this study suggests detailed mechanisms underlying the effects of the Pd(P) thickness on the morphology and growth of the (Cu,Ni)6Sn5formed during the reflow process.