The effect of Cu substrate texture on the intermetallic compounds (IMCs) growth at a Sn3.5Ag–Cu interface

Abstract

The effect of Cu substrates texture on morphology and growth behavior of intermetallic compounds (IMCs) during reflowing and aging time were systematically investigated. The IMCs formed at Sn3.5Ag/(220) Cu and Sn3.5Ag/(200) Cu interface showed significant difference. After reflowing, the Cu6Sn5 grains in the both couples are all rounded, but more protruded and thinner at Sn3.5Ag/(200) Cu interface due to lower IMC/solder interfacial energy and smaller quantity of dissolution Cu atoms for (200) Cu substrate. At aging process, for IMCs formed on two different textured substrates, the Cu6Sn5 and Cu3Sn exhibited reciprocal inhibition within 48 h, and the whole thickness of IMCs (Cu6Sn5+Cu3Sn) increases with aging time prolonged, proportional to the square root of aging time. The whole IMCs at Sn3.5Ag/(220) Cu interface is thicker than that at Sn3.5Ag/(200) Cu interface, with a reaction constant of 1.849 × 10−17 and 5.39 × 10−18 m2/s for IMCs growth respectively.