(中南大學 材料科學與工程學院，長沙 410083)
摘 要: 研究微量稀土La在釬焊和時效過程中對Sn-3.0Ag-0.5Cu無鉛釬料與銅基板的釬焊界面及釬料內(nèi)部金屬間化合物(IMC)的形成與生長行為的影響。結(jié)果表明：釬焊后釬焊界面形成連續(xù)的扇形Cu6Sn5化合物層，其厚度隨La含量的增加而減小；在150 ℃時效100 h后，連續(xù)的Cu3Sn化合物層在Cu6Sn5化合物層和銅基板之間析出，且Cu6Sn5層里嵌有Ag3Sn顆粒；界面金屬間化合物總厚度隨時效時間的延長而增厚，且在相同時效條件下隨La含量的增加而減小；時效過程中金屬間化合物生長動力學的時間系數(shù)(n)隨著La含量的增加逐漸增大；釬焊后釬料內(nèi)部Ag仍以共晶形式存在，時效后Ag3Sn顆粒沿釬料內(nèi)部的共晶組織網(wǎng)絡析出。
關鍵字: Sn-Ag-Cu無鉛釬料；La；釬焊；時效；金屬間化合物
（School of Materials Science and Engineering, Central South University, Changsha 410083, China）
Abstract:The effects of minor La on the formation and growth behaviors of intermetallic compounds at Sn-3.0Ag-0.5Cu lead-free solder alloy/copper substrate interface and inside the solders during soldering and aging were investigated. The results show that Cu6Sn5 layer formed at the interface exhibits a continuous scallop-shaped structure after soldering, the thickness of Cu6Sn5 layer decreases with increasing La content. A thin Cu3Sn intermetallic compounds layer forms at the interface between Cu6Sn5 layer and Cu substrate after aging at 150 ℃ for 100 h. Ag3Sn particles are embedded to the Cu6Sn5 layer. The total intermetallic compounds thickness increases with prolonging aging time, and decreases with increasing La content under the same aging condition. The time exponent (n) in growth kinetic of intermetallic compounds layer during aging increases with increasing La content. Ag elements exist in Sn-Ag eutectic structures after soldering, and Ag3Sn particles are precipitated along the eutectic bonds after aging.
Key words: Sn-Ag-Cu lead-free solder; La; soldering; aging; intermetallic compound
