Lead free Soldering

In this research area, potential lead-free solder alloys and corresponding lead-free surface finishes (board and component) are being identified to replace eutectic 63Sn-37Pb solder in harsh environment applications. The primary goal is to develop a fundamental understanding of alternate solder alloys that will meet the high reliability, and high volume low cost manufacturing needs of the vehicle industry. Deliverables include recommended solder alloys; solderability (wetting) measurements; thermal cycling reliability data, stress-strain and creep results as a function of temperature, constitutive and solder fatigue models; and processing recommendations. For example the figure below shows the effect of Aging on SAC105 Creep Properties. 

lead free creep range

The following movie is a visualization of the wetting of SAC405 Solder to Ni-Au in Real-Time.

 

The next movie shows a tin whisker on a silver system that is heated linearly from room temperature to above the melting temperature of tin. The movie was recorded in real-time with a scanning electron microscope.  


Area-Leader

Dr. Michael Bozack (Research Leader)

Objectives

  • Develop a comprehensive understanding of aging behavior in lead free solder joints
  • Fully understand microstructural evolution (phase/grain growth) during aging
  • Identify SACX alloys where aging effects are mitigated

Project Titles

  • P10-301 Constitutive Modeling of leadfree solder alloys Including aging
  • P10-302 Cyclic Stress-Strain behavior of leadfree alloys
  • P10-303 Aging behavior of SACX alloy

Posters

  • Reduction of Lead Free Solder Aging Effects Using Doped SAC Alloys - Zijie Cai (ME)
  • Aging Induced Microstructure Evolution of Doped Lead Free Solders - Zijie Cai (ME)
  • Aging Induced Relaxation of Residual Stresses in Lead Free Solders - Zijie Cai (ME)
  • Characterization of Hysteresis Loop Evolution in Aged Lead Free Solders - Muhannad Mustafa (ME), Zijie Cai (ME)
  • Determination of Material Properties of Solder Joints by Nano-Indentation Testing - Muhannad Mustafa (ME)
  • Development and Construction of an Iosipescu Shear Test Fixture for Solders  - Muhannad Mustafa (ME), Jordan Roberts (ME)
  • Effects of Aging on the Anand Constants for Lead-Free Solder Alloys - Mohammad Motalab (ME)
  • Sensitivity of the Stress-Strain Behavior of Lead-Free Solders to Changes in the Anand Constants - Mohammad Motalab (ME)

Publications

Reviews