微量Co元素添加對Sn-0.7Cu無鉛銲錫合金性質的影響研究

Abstract

本研究主要係探討添加微量Co元素對Sn-0.7Cu銲錫合金熔點、機械性質、顯微組織及接合性能方面之影響。 由示差掃描熱量分析中得知添加Co元素後，合金熔點約為227.3℃，且由單一放熱峰得知為共晶組成；顯微組織分析顯示Sn-0.7Cu合金以β-Sn+網狀β-Sn+Cu6Sn5共晶組成為主，添加0.05wt%Co後會析出顆粒狀Sn-Cu-Co化合物，添加0.1wt%Co後則會形成長條狀的Sn2Co。在拉伸性能方面可得知Co元素的添加可改善Sn-0.7Cu合金之強度及延展性。 此外由接合性能實驗結果可發現，Co元素添加可抑制Cu3Sn界面反應物生成，且可增加Sn-0.7Cu銲錫合金銲點接合強度，而隨高溫儲存時間的增加，因為界面反應層的成長，造成銲點衰弱而使破斷位置由銲錫處，移至銲錫與界面反應層處。

In order to study the effect of the addition of Co to the Sn-0.7Cu solder, the formation of an IMC at the interface between Sn-0.7Cu-xCo(x=0, 0.05, 0.1wt%) solders and Cu Substrate were investigated, and the joint strength was also evaluated by tensile test. From the DSC analysis of Sn-0.7Cu alloys containing various amounts of Co, it was found that the eutectic reaction occurred around 227.3°C. The microstructure of Sn-0.7Cu solder was identified asβ-Sn plus eutectic (β-Sn+Cu6Sn5) by SEM and EDS. Sn-Cu-Co compounds can be found in Sn-0.7Cu solder with 0.05wt%Co. Sn2Co IMCs can be observed in Sn-0.7Cu solder with 0.1wt%Co. Additionally, the results of the tensile test show that the addition of Co elements can improve the mechanical properties of the solder. After high temperature storage test at 150℃, the growth of interfacial Cu3Sn IMCs was inhibited by the adding of Co into the Sn-0.7Cu solder. The addition of Co elements can improve the joint strength of the solder joints.