Sn-3Ag-XCu (X=0.0~0.9)三元銲料在去離子水中的電化學遷移行為

Electrochemical Migration of Sn-3Ag-XCu (X=0.0~0.9) Ternary Solder in Deionized Water

Sn-3Ag-XCu(X=0.0～0.9) 迴銲於兩銅墊上，完全浸泡於去離子水中做為陰陽兩極，兩極間施以2V～3V直流偏壓，研究其電化學遷移現象。結果顯示：銲料中銅含量由0.0增高至0.9wt%時，此銲料系統的電化學遷移現象趨向嚴重。能量散佈光譜（Energy Dispersive Spectrometer, EDS）分析顯示：在遷移100秒後兩極間樹狀析出物的銅含量隨著此三元銲料系統中銅含量增多而增加；X光光電子光譜儀（X-ray photoelectron spectrometer, XPS）分析顯示兩銲錫間電化學遷移產物之結果之主要成份為Sn、SnO2、Ag2O、CuO，所含的銀與銅比例隨著遷移增加而減少，錫則增加。Sn、Ag、Cu在單一金屬及Sn-3Ag-XCu(X=0.0～0.9) 三元銲料系統的電化學動態極化法（potentiodynamic polarization）解析有助於電化學遷移機理之理解。

Sn-3Ag-XCu(X=0.0~0..9) solders were reflowed on two copper pads,between/which 2-3V DC voltage was employed to investigate the electrochemical migration in deionized water. The electrochemical migration of Sn-3Ag-XCu(X=0.0~0.9) became more active with increasing the Cu content from 0.0 to 0.9 wt%. EDS analysis showed that the Cu concentration in the dendritic precipitate produced between two solder electrodes increases with increasing the Cu content in the ternary solder system. XPS spectra on the precipitate formed between two electrodes displayed that the main components of the precipitate are Sn, SnO2, Ag2O, CuO. Weight ratios of Ag and Cu to the total precipitate tended to decrease but that of Sn increase with the migration time. Potentiodynamic polarization curves of pure Sn, Ag, Cu metals and of the Sn-3Ag-XCu(X=0.0~0.9) were compared. The mechanism of electrochemical migration these of alloys for the solders Sn-3Ag-XCu(X=0.0~0.9) solders in deionized water was proposed.