1 Copyright © 2015 by ASME Proceedings of the ASME 2015 International Technical Conference and Exhibition on Packaging and Integration of Electronic and Photonic Microsystems and the ASME 2015 13th International Conference on Nanochannels, Microchannels, and Minichannels InterPACKICNMM2015 July 6-9, 2015, San Francisco, CA, USA InterPACKICNMM2015-48624 CHARACTERIZATION OF DOPED SAC SOLDER MATERIALS AND DETERMINATION OF ANAND PARAMETERS Sudan Ahmed, Munshi Basit, Jeffrey C. Suhling, Pradeep Lall Department of Mechanical Engineering, and Center for Advanced Vehicle and Extreme Environment Electronics (CAVE 3 ) Auburn University Auburn, AL 36849 Phone: +1-334-844-3332 FAX: +1-334-844-3124 E-Mail: jsuhling@auburn.edu ABSTRACT In the electronic packaging industry, it is important to be able to make accurate predictions of board level solder joint reliability during thermal cycling exposures. The Anand viscoelastic constitutive model is often used to represent the material behavior of the solder in finite element simulations. This model is defined using nine material parameters, and the reliability prediction results are often highly sensitive to the Anand parameters. In present work, three new doped lead free solder materials recommended for high reliability applications have been chemically analyzed and then mechanically tested in order to determine the nine Anand parameters. The alloys are referred to as Ecolloy (SAC_R), CYCLOMAX (SAC_Q), and Innolot by their vendors. The first two doped alloys (SAC_R and SAC_Q) were found to be composed of Sn, Ag, Cu, and a single X-element dopant. Such solders are commonly referred to as SAC-X in the literature. For the third material (Innolot), three different dopants are present along with Sn, Ag and Cu. The EDX method was used to determine the approximate chemical composition of the materials, and Bismuth (Bi) was found to be the X-additive for both SAC_R and SAC_Q. In addition, the SAC_R material was found to have no silver (Ag), which is the reason it is marketed as a low cost (economy) material. The nine Anand parameters were determined for each unique solder alloy from a set of uniaxial tensile tests performed at several strain rates and temperatures. Testing conditions included strain rates of 0.001, 0.0001, and 0.00001 (sec -1 ), and temperatures of 25, 50, 75, 100, and 125 C. The Anand parameters were calculated from each set of stress-strain data using an established procedure that is described in detail in the paper. The mechanical properties and the values of Anand parameters for these new doped alloys were compared with those for standard SAC105 and SAC405 lead free alloys. Although the SAC_R material does not have any silver, it was shown to have better mechanical behavior than SAC105 due to the presence of Bismuth (Bi) along with a little higher percentage of Copper (Cu). The SAC_Q and Innolot materials were shown to have significantly higher strength than SAC405. After deriving the Anand parameters for each alloy, the stress- strain curves have been calculated for various conditions, and excellent agreement was found between the predicted results and experimental stress-strain curves. KEYWORDS Lead Free Solder, Stress-Strain Curve, Doped Alloy, Anand Model, Constitutive Relations INTRODUCTION The electronic packaging industry has widely transitioned to Pb-free solders due to environmental concerns. Among the diversity of Pb-free solders, the Sn-Ag-Cu (SAC) alloys have become the most popular and are often considered to be the standard lead-free alloys. NEMI (National Electronics Manufacturing Initiative) recommended to replace Sn-Pb