Late News Poster Session: Electronic Materials
Program Organizers: TMS Administration

Monday 5:30 PM
February 28, 2022
Room: Exhibit Hall C
Location: Anaheim Convention Center

C-4: Correlation between Crystallographic Microstructure of Electrodeposits and Adsorption of Additives through Electrochemical Calculations at Feature Scale: Han-Kyun Shin¹; Yeon-Soo Jung¹; Hyun Park¹; Hyojong Lee¹; ¹Dong-A University
Electroplating technology has been used for filling damascene and PCB patterns having a scale of several nanometers to several hundreds of micrometers. In terms of mass transfer in aqueous solution, copper ions, Cl^-, and organic additives are known to have a diffusion coefficient of ~10^-10 m²s^-1, which can be inferred to have an average moving distance of ~10 µm per second. It can be expected that the concentration gradient of these materials in the pattern is not large at the nanoscale, and in filling the nanoscale pattern, the competitive adsorption of organic additives is important. However, when the pattern scale is tens of micrometers or more, the concentration gradient inside the pattern by mass transfer plays an important role. Here, we try to explain the crystallographic microstructure measured through EBSD in connection with the electrochemical calculation results in PCB and TSV patterns.

C-5: Effect of Antimony on the Microstructure Evolution and Mechanical Properties of Near Eutectic Sn-Bi and Sn-Bi-Ag Alloys: Hannah Fowler¹; Raiyo Aspandiar²; Yaohui Fan¹; Sukshitha Achar Puttur Lakshminarayana¹; Ganesh Subbarayan¹; John Blendell¹; Carol Handwerker¹; ¹Purdue University; ²Intel
Eutectic and near-eutectic Sn-Bi alloys are promising low-temperature replacements for some high-Sn Pb-free solder applications, allowing reflow temperatures to be reduced by 70˚C relative to Sn-Ag-Cu alloys, the most commonly used Pb-free solder. Low-temperature reflow using eutectic Sn-Bi can reduce component warpage and eliminate a range of warpage-induced solder joint defects, including head-on-pillow defects. First generation near-eutectic Sn-Bi alloys show excellent thermal cycling reliability but poor drop-shock performance. Small additions of Sb to Sn-Bi and Sn-Bi-Ag eutectic alloys can significantly increase ductility and reduce strain-rate sensitivity without decreasing the yield strength, combinations shown to improve shock-drop performance. In this presentation, we will discuss the impact of Ag and Sb additions on solidification and microstructure evolution in eutectic Sn-Bi alloys on Cu and ENIG substrates and how the resulting compositions and microstructures affect solder joint mechanical properties, particularly isothermal mechanical fatigue and crack path, and relate this behavior to drop-shock testing.