Microstructural Evaluation of Bi-Ag and Bi-Sb Lead-Free High-Temperature Solder Candidates on Copper Substrate with Multiple Reflow Number

• Published in: Applied Mechanics and Materials Vol. 564; no. Advances in Mechanical and Manufacturing Engineering; pp. 388 - 393
• Main Authors: Nahavandi, Mahdi, Mohamed Ariff, Azmah Hanim, Baserfalak, F., Ismarrubie, Z.N.
• Format: Journal Article
• Language: English
• Published: Zurich Trans Tech Publications Ltd 01.06.2014
• Subjects: Alloys; Antimony; Copper; INTERMETALLIC COMPOUNDS; Lead free; Metallurgy; Microstructure; MICROSTRUCTURES; REFLOWING; Silver; SOLDERING ALLOYS; Solders; Lead-Free Solder; Bi-Sb Solder Alloy; Intermetallic Compound (IMC); Multiple Reflow Number; Grain Boundary Grooving; Bi-Ag Solder Alloy
• ISBN: 9783038351085; 3038351083
• ISSN: 1660-9336; 1662-7482; 1662-7482
• DOI: 10.4028/www.scientific.net/AMM.564.388

An impetus has been provided towards the development of lead-free solders by worldwide environmental legislation that banned the use of lead in solders due to the lead toxicity.This study focus on Bi-Ag and Bi-Sb solder alloys, in compositions from 1.5 to 5 wt % Ag and Sb. The effects of Ag and Sb amount, and reflow number on the microstructure and morphology of solder bulk were analysed by optical microscope and scanning electron microscope-energy dispersive X-ray. Based on the results, the grain boundary grooving was observed in all samples except Bi-5Sb in all three reflows. Metallurgical and chemical reaction between interface and solders were found in Bi-5Sb solder alloys in different reflow numbers which lead to appearance of Cu3Sb intermetallic compound layer at the interface. Reflow numbers had a significant effect on the size of Cu-rich phase. Also it was observed that, with increasing reflow number Bi-Cu phase found in Bi-2.5Sb solder dissolves into the solder bulk.