Growth Pattern of Intermetallic Compound (IMC) Layer after Lead-tin Soldering for LTCC Film

Aerospace microwave LTCC substrates are all-gold material systems with Pt and Au as the main components of the lead-tin resistant solder film, which forms an intermetallic compound (IMC) layer at the solder interface after 63Sn-37Pb soldering. Structure and composition of LTCC film are analyzed, while the risk of solder joint in the subsequent assembly is evaluated. Based on the diffusion principle, the relationship between the growth rate of IMC layer and temperature after soldering is established. The tolerance of LTCC solder joints to different baking temperatures is also calculated based on the IMC layer growth rate. According to the research results of this paper, the recommended baking temperature for post-solder assembly is up to 120°C.