Lead Free Solders

Potential health hazards due to the toxic nature of lead has prompted the electronics industry to establish regulations regarding its usage. Europe, Japan, and parts of the United States have implemented the regulations suggested by the Restriction of Hazards Substances (RoHS) and Waste from Electrical and Electronic Equipment (WEEE) directives. Due to this, eutectic tin-lead alloy in the solder joint has been replaced with lead free Sn-Ag-Cu (SAC) alloys in most applications. Although this change has resulted in benefits regarding the health and safety on individuals, it also has produced new challenges. The microstructure, mechanical response, and failure behavior of lead free solder joints in electronic assemblies are constantly evolving when exposed to isothermal aging and/or thermal cycling environments. It is observed that the material behavior variations of SAC lead free solders during room temperature (25°C) aging and elevated temperature (125°C) aging are unexpectedly large and universally detrimental to reliability. Such effects for lead free solder materials are especially important for the harsh applications environments present in high performance computing and in automotive, aerospace, and defense applications.

lead free creep range


Area-Leader

Dr. Jeffrey Suhling (Research Leader), Dr. S'ad Hamasha (Research Leader), Dr. Michael Bozack (Research Leader)

Objectives

  • Measure Stress-Strain and Creep Curves for Lead Free Solders over a Wide Range of Aging Temperatures and Aging Times
  • Study Different SAC Alloys
       -- SACN05: SAC105, SAC205, SAC305, SAC405
  • Explore Effects of Dopants to Reduce Aging Effects
       -- SAC+Bi, SACX307, SAC305X, etc.
  • Understand the Effects of Aging on Solder Microstructure
  • Provide the Basic Constitutive Laws and Mechanical Properties of Different Lead Free Solder Materials for Use in Finite Element Reliability Simulations
  • Investigate the Uniaxial and Tensile Properties of SAC305 and Doped SAC Solders at Very High Temperatures (Project: P17-302)
  • Determine Anand Model Parameters (Project: P17-302)
  • Investigate the Correlation of Anand Model and Experimental Results (Project: P17-302)
  • Measure Nanomechanical Properties of IMCs in SAC Solder Joints after Long Term Isothermal Aging at Room and Elevated Temperatures (Project: P16-301)
  • Prepare Solder Joint Samples and Age Them Isothermally for 6 Months at 125 °C to Grow Intermetallics at the Solder-Cu Pad Interface and Solder Bulk; Identify and Observe Different IMC Formation with EDS and SEM Technique (Project: P16-301)
  • Perform Nanoindentation Test and Evaluate Average Modulus and Hardness of IMCs at Temperature Range of 25-125 °C (Project: P16-301)
  • Perform Nanoindentation Creep Test for Various IMCs at 25 and 100 °C; Measure Variation in Creep Strain Rate with Stress and Find the Creep Exponent (Project: P16-301)
  • Prepare Super BGA (SBGA) Solder Joint Cross-Sections  (Project: P16-301)
  • Observe and Identify β-Sn Dendrites in Different Grains Using a Polarized Optical Microscope (Project: P16-301)
  • Perform Aging at 125 °C for 5 Different Time Intervals (0, 1, 5, 10, 30 Days) (Project: P16-301)
  • Perform Nanoindentation to Obtain Mechanical Properties (Modulus, Hardness and Creep Behavior) of Both β-Sn and IMC particles with Different Aging Times (Project: P16-301)
  • Investigate the Effect of the Value of the Solder Joint Poisson's Ratio on the Finite Element Results for BGA Components Subjected to Thermal Cycling (Project: P16-303)
  • Determine Plastic Energy Dissipation per Cycle in the Critical Solder Ball for Different Values of the Solder Poisson's Ratio (Project: P16-303)
  • Establish the Fact that the Specified Poisson's Ratio Strongly Affects the Mechanical Response and Simulation Results (Project: P16-303)
  • Experimental Characterization of Poisson's Ratio for Different SAC Alloys at Different Temperatures, Strain Rates, Solidification Profiles and Aging Conditions (Project: P16-303) 

Project Titles

  • P17-302  High Temperature Tensile and Creep Behavior of Lead Free Solders 
  • P16-301 Aging Behavior of Solder Joints at Elevated Temperatures
  • P16-303 The Poisson's Ratio of Lead Free Solder

Posters

  • A Comparative Study of the High Temperature Mechanical Behavior of Lead Free Solders - Mohammad Alam (ME), Rafidh Hassan (ME)
  • Effects of High Temperature Aging on the Mechanical Behavior of Lead Free Solders - Mohammad Alam (ME), Rafidh Hassan (ME)
  • Mechanical Characterization of Intermetallic Compounds in SAC Solder Joints at Elevated Temperature - Abdullah Fahim (ME), Sudan Ahmed (ME)
  • Nanoindentation Measurements of the Mechanical Properties of Individual Phases within Lead Free Solder Joints Subjected to Isothermal Aging - Abdullah Fahim (ME), Sudan Ahmed (ME)
  • The Effects of Temperature, Strain Rate, Solidification Profile, and Aging on the Poisson's Ratio of SAC Lead Free Solders - KM Rafidh Hassan (ME), Mohammad S. Alam (ME) 

Representative Recent Publications

Fahim, A., Ahmed, S., Suhling, J.C., Lall, P., Nanomechanical Characterization of Intermetallic Compounds in Lead Free Solder Joints, Proceedings of the IEEE 2018 Electronic Components and Technology Conference (ECTC2018), San Diego, CA, May 29-June 1, 2018.

Ahmed, S., Wu, J., Fu, N., Suhling, J.C., Lall, P., Quantification and Modeling of Microstructural Evolution in Lead Free Solders During Long Term Isothermal Aging, Proceedings of the IEEE 2018 Electronic Components and Technology Conference (ECTC2018), San Diego, CA, pp. 162-171, May 29-June 1, 2018.

Chowdhury, M.M., Hoque, M.A., Ahmed, S., Suhling, J.C., Hamasha, S., Lall, P., Effects of Mechanical Cycling on the Microstructure of SAC305 Lead Free Solder, Proceedings of the IEEE 2018 Intersociety Conference on Thermal and Thermomechanical Phenomena in Electronic Systems (ITherm2018), San Diego, CA, pp. 1324-1332, May 29-June 1, 2018.

Hassan, KM Rafidh, Alam, M.S., Basit, M., Suhling, J.C., Lall, P., The Influence of Poisson's Ratio on the Reliability of SAC Lead Free Solder Joints, Proceedings of the IEEE 2018 Intersociety Conference on Thermal and Thermomechanical Phenomena in Electronic Systems (ITherm2018), San Diego, CA, pp. 1207-1216, May 29-June 1, 2018.

Alam, M.S., Hassan, KM Rafidh, Suhling, J.C., Lall, P., High Temperature Mechanical Behavior of SAC and SAC+X Lead Free Solders, Proceedings of the IEEE 2018 Electronic Components and Technology Conference (ECTC2018), San Diego, CA, pp. 1781-1789, May 29-June 1, 2018.

Alam, M.S., Hassan KM Rafidh, Suhling, J.C., Lall, P., A Comparative Study of the High Temperature Mechanical Behavior of Lead Free Solders, Proceedings of the IEEE 2018 Intersociety Conference on Thermal and Thermomechanical Phenomena in Electronic Systems (ITherm2018), San Diego, CA, pp. 1314-1323, May 29-June 1, 2018.

Ahmed, S., Suhling, J.C., Lall, P., Evaluation of Aging Induced Microstructural Evolution in Lead Free Solders Using Scanning Probe Microscopy, Proceedings of the IEEE 2018 Intersociety Conference on Thermal and Thermomechanical Phenomena in Electronic Systems (ITherm2018), San Diego, CA, pp. 1062-1070, May 29-June 1, 2018.

Chowdhury, M.M., Hoque, M.A., Fu, N., Suhling, J.C., Hamasha, S., Lall, P., Characterization of Material Damage and Microstructural Evolution Occurring in Lead Free Solders Subjected to Cyclic Loading, Proceedings of the IEEE 2018 Electronic Components and Technology Conference (ECTC2018), San Diego, CA, pp. 865-874, May 29-June 1, 2018.

Wu, J., Ahmed, S., Suhling, J.C., Lall, P., Investigation of Microstructural Evolution in SAC Solders Exposed to Short-Term and Long-Term Aging, Proceedings of the IEEE 2018 Intersociety Conference on Thermal and Thermomechanical Phenomena in Electronic Systems (ITherm2018), San Diego, CA, pp. 1234-1242, May 29-June 1, 2018.

Fahim, A., Ahmed, S., Suhling, J.C., Lall, P., Mechanical Characterization of Intermetallic Compounds in SAC Solder Joints at Elevated Temperatures, Proceedings of the IEEE 2018 Intersociety Conference on Thermal and Thermomechanical Phenomena in Electronic Systems (ITherm2018), San Diego, CA, pp. 1081-1090, May 29-June 1, 2018.

Hoque, M.A., Chowdhury, M.M., Fu, N., Suhling, J.C., Hamasha, S., Lall, P., Evolution of the Cyclic Stress-Strain and Constitutive Behavior of Doped Lead Free Solder During Fatigue Testing, Proceedings of the IEEE 2018 Intersociety Conference on Thermal and Thermomechanical Phenomena in Electronic Systems (ITherm2018), San Diego, CA, pp. 1387-1395, May 29-June 1, 2018.

Lall, P., Yadav, V., Suhling, J., Locker, D., Effect of Prolonged Storage on High Strain Rate Mechanical Properties of SAC-Q Leadfree Solder at High Operating Temperature, Proceedings of the IEEE 2018 Intersociety Conference on Thermal and Thermomechanical Phenomena in Electronic Systems (ITherm2018), San Diego, CA, pp. 1296-1308, May 29-June 1, 2018.

Lall, P., Yadav V., Zhang, D., Suhling, J., Reliability of SAC Leadfree Solders in Automotive Underhood Temperature-Vibration, Proceedings of the IEEE 2018 Intersociety Conference on Thermal and Thermomechanical Phenomena in Electronic Systems (ITherm2018), San Diego, CA, pp. 1255-1269, May 29-June 1, 2018.

Ahmed, S., Suhling, J.C., Lall, P., The Anand Parameters of Aging Resistant Doped Solder Alloys, Proceedings of the IEEE 2017 Intersociety Conference on Thermal and Thermomechanical Phenomena in Electronic Systems (ITherm2017), Orlando, FL, pp. 1416-1424, May 30-June 2, 2017.

Fu, N., Ahmed, S., Suhling, J.C., Lall, P., Visualization of Microstructural Evolution in Lead Free Solders During Isothermal Aging Using Time-Lapse Imagery, Proceedings of the IEEE 2017 Electronic Components and Technology Conference (ECTC2017), Orlando, FL, pp. 429-440, May 30-June 2, 2017.

Alam, M.S., Suhling, J.C., Lall, P., High Temperature Tensile and Creep Behavior of Lead Free Solders, Proceedings of the IEEE 2017 Intersociety Conference on Thermal and Thermomechanical Phenomena in Electronic Systems (ITherm2017), Orlando, FL, pp. 1229-1237, May 30-June 2, 2017.

Fahim, A., Ahmed, S., Suhling, J.C., Lall, P., Nanomechanical Characterization of IMCs Formed in SAC Solder Joints Subjected to Isothermal Aging, Proceedings of the IEEE 2017 Intersociety Conference on Thermal and Thermomechanical Phenomena in Electronic Systems (ITherm2017), Orlando, FL, pp. 1398-1408, May 30-June 2, 2017.

Fu, N., Suhling, J.C., Hamasha, S., Lall, P., Evolution of the Cyclic Stress-Strain and Constitutive Behaviors of SAC305 Lead Free Solder During Fatigue Testing,  Proceedings of the IEEE 2017 Intersociety Conference on Thermal and Thermomechanical Phenomena in Electronic Systems (ITherm2017), Orlando, FL, pp. 1353-1360, May 30-June 2, 2017.

Chowdhury, M.M., Fu, N., Suhling, J.C., Lall, P., Evolution of the Cyclic Stress-Strain Behavior of Doped SAC Solder Materials Subjected to Isothermal Aging, Proceedings of the IEEE 2017 Intersociety Conference on Thermal and Thermomechanical Phenomena in Electronic Systems (ITherm2017), Orlando, FL, pp. 1369-1379, May 30-June 2, 2017.

Ahmed, S., Hasnine, M., Suhling, J.C., Lall, P., Mechanical Characterization of SAC Solder Joints at High Temperature Using Nanoindentation, Proceedings of the IEEE 2017 Electronic Components and Technology Conference (ECTC2017), Orlando, FL, pp. 1128-1135, May 30-June 2, 2017.

Fu, N., Suhling, J.C., Lall, P., Cyclic Stress-Strain Behavior of SAC305 Lead Free Solder: Effects of Aging, Temperature, Strain Rate, and Plastic Strain Rate, Proceedings of the IEEE 2016 Electronic Components and Technology Conference (ECTC2016), Las Vegas, NV, pp. 1119-1127, May 31-June 3, 2016.

Fahim, A., Ahmed, S., Chowdhury, M.M., Suhling, J.C., Lall, P., High Temperature Creep Response of Lead Free Solders, Proceedings of the IEEE 2016 Intersociety Conference on Thermal and Thermomechanical Phenomena in Electronic Systems (ITherm2016), Las Vegas, NV, pp. 1218-1224, May 31-June 3, 2016.

Alam, M.S., Basit, M., Suhling, J.C., Lall, P., Mechanical Characterization of SAC305 Lead Free Solder at High Temperatures, Proceedings of the IEEE 2016 Intersociety Conference on Thermal and Thermomechanical Phenomena in Electronic Systems (ITherm2016), Las Vegas, NV, pp. 755-760, May 31-June 3, 2016.

Fu, N., Suhling, J.C., Mustafa, M., Lall, P., Aging Induced Evolution of the Cyclic Stress-Strain Behavior of Lead Free Solders, Proceedings of the IEEE 2016 Intersociety Conference on Thermal and Thermomechanical Phenomena in Electronic Systems (ITherm2016), Las Vegas, NV, pp. 737-745, May 31-June 3, 2016.

Motalab, M., Mustafa, M., Suhling, J.C., Lall, P., Improved Predictions of Cyclic Stress-Strain Curves for Lead Free Solders using the Anand Viscoplastic Constitutive Model, Proceedings of the IEEE 2016 Intersociety Conference on Thermal and Thermomechanical Phenomena in Electronic Systems (ITherm2016), Las Vegas, NV, pp. 471-480, May 31-June 3, 2016.

Ahmed, S., Basit, M., Suhling, J.C., Lall, P., Effects of Aging on SAC-Bi Solder Materials, Proceedings of the IEEE 2016 Intersociety Conference on Thermal and Thermomechanical Phenomena in Electronic Systems (ITherm2016), Las Vegas, NV, pp. 746-754, May 31-June 3, 2016.

Chowdhury, M.M., Ahmed, S., Fahim, A., Suhling, J.C., Lall, P., Mechanical Characterization of Doped SAC Solder Materials at High Temperature, Proceedings of the IEEE 2016 Intersociety Conference on Thermal and Thermomechanical Phenomena in Electronic Systems (ITherm2016), Las Vegas, NV, pp. 1201-1208, May 31-June 3, 2016.

Basit, M., Ahmed, S., Motalab, M., Roberts, J.C., Suhling, J.C., Lall, P., The Anand Parameters for SAC Solders after Extreme Aging, Proceedings of the IEEE 2016 Intersociety Conference on Thermal and Thermomechanical Phenomena in Electronic Systems (ITherm2016), Las Vegas, NV, pp. 440-447, May 31-June 3, 2016.

 

Publications

Reviews