Cu含量对Sn基无铅钎料组织、界面反应影响

Effect of Cu content on microstructure and interfacial reactions of Sn-based lead-free solders

研究了Cu含量对Sn-xCu(x=0.7%,2%)、Sn-9Zn-xCu(x=0,2%,10%)两种无铅钎料的基体组织以及与Cu基板短时间钎焊时界面金属间化合物(IMC)生长行为的影响.结果表明,当Sn-Cu钎料中Cu的含量为2%时,基体中IMC粗化为块状的Cu6Sn5相;对于Sn-9Zn-xCu钎料合金,2%Cu元素的加入使得Sn-9Zn基体中长针状的富Zn相转化为Cu5Zn8相以及细小的富Zn相,而当Cu含量达到10%时,钎料基体中的IMC为CuZn相与Cu6Sn5相.在260℃短时间钎焊下,Cu含量的增加加速了Sn-xCu/Cu界面IMC的粗化和生长;而对于Sn-9Zn-xCu/Cu,Cu含量的增加却明显降低了界面IMC的生长速率.同时分析、讨论了界面IMC随钎焊时间变化的生长行为.

Two kinds of lead-free solders, Sn-xCu（x = 0.7%,2%） and Sn-9Zn-xCu（x = 0,2%, 10%） were chosen. The microstructure as well as interracial reactions between the selected lead-free solders and Cu substrate within short soldering time was studied. The intermetallic compounds （IMC） are coarsened into nubbly Cu6Sns phase by adding excessive Cu into Sn-Cu solder alloy. For Sn-gZn-xCu solder alloys, the long needle-like Zn rich phase which is the mainly existing form of Zn in Sn-Zn solders is transformed into Cu^Zn8 phase and fine Zn rich phase by the addition of 2% Cu, while CuZn phase and Cu6Sn5 phase are formed in Sn-9Zn-10Cu bulk alloy. When soldering within short time under 260 ℃, the ripening and growth of IMC at Sn-xCu/Cu interface are accelerated with increasing Cu content in Sn-Cu solders. However, for Sn-9Zn-xCu/Cu joints, the growth rate of IMC is decreased markedly with increasing Cu addition in Sn-Zn based solders, and Cu6Sn5 phase rather than Cu5Zn8 phase is formed at the interface when the Cu content is up to 10%. Meanwhile the growth behavior of IMC with the variation of soldering time is analyzed and discussed.