Sn-0.7Cu-xZn無鉛銲錫合金之界面反應及銲點強度研究

Abstract

本研究主要為探討添加微量Zn元素對Sn-0.7Cu銲錫合金之顯微組織、機械性質以及接合後之性質。研究中先以熱浸銲方式製備Cu基材對銲試棒，並且將試棒進行150℃高溫儲存實驗0~500小時後，分別進行顯微組織觀察，界面反應層分析及銲點拉伸強度試驗。 經過分析後得知Sn-0.7Cu合金銲點之接合界面顯微組織係由Sn基地+Cu6Sn5介金屬化合物所組成。合金的銲點經150℃高溫儲存處理300小時後，其界面反應層會形成第二層界面反應物Cu3Sn，但是加入Zn元素之Sn-0.7Cu-xZn合金並沒有發現Cu3Sn，惟合金銲點之界面反應層厚度有增加的趨勢。發現Zn元素添加可抑制Cu3Sn界面反應物生成，且銲點接合強度優於Sn-0.7Cu銲錫合金，隨高溫儲存時間的增加，破斷位置仍保持在銲錫處。此點亦說明在Sn-0.7Cu合金中添加微量的Zn元素可以提升Sn-0.7Cu合金銲點在長時間儲放或操作後的信賴性。

The effects of Zn additions on the interfacial reactions with Cu substrates of Sn-0.7Cu (all in wt.% unless specified otherwise) Pb-free solders were investigated. This study was focused on the intermetallic compound (IMC) growth, interfacial reaction and the joint strength as a function of thermal aging and solder composition. Thermal aging was conducted at 150℃ for up to 500 h to accelerate the interfacial reactions between solders and Cu substrates. The growth of IMCs (Cu6Sn5 and Cu3Sn) in Zn-added solders was slower than those without Zn additions. The growth of the Cu3Sn phase, in particular, was drastically reduced in the Zn-added solders. The Zn addition was effective in reducing IMCs’ growth (especially Cu3Sn IMCs). In addition, void formation at the interfaces of Sn-0.7Cu was dramatically suppressed by Zn addition. Finally, a mechanism for the beneficial effects of Zn additions on the reduction of IMCs’ growth was discussed. The addition of Zn elements can effectively improve the joint strength of the solder joints.