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

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 Cu 6 Sn 5 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 Cu 6 Sn 5 and Cu 3 Sn exhibited reciprocal inhibition within 48 h, and the whole thickness of IMCs (Cu 6 Sn 5 +Cu 3 Sn) 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 m 2 /s for IMCs growth respectively.