1. Characterization of 1mm lead-free joints

2. Test results (DIC 2D) 2 3 1 4

3. Experimental results Measured stress-strain curves:  Improved resolution/noise with 2D DIC: Displacement +/-0.2 microns, strain +/- 2E-4 Correction of the out of plane displacement effects  Apparent properties and variability:  Large variability between plates, lower variability for a given plate  effects of processing parameters / microstructure ?

4. Plasticity - damage evolution (1B)

5. Plasticity - damage evolution (2B)

6. Plasticity - damage evolution (3A)

7. Plasticity - damage evolution (4A)

8. Plasticity - Damage evolution: remarks Need to distinguish two phenomena:  Elasto-plastic deformation: global behavior of the solder joint  Failure : local behavior, depends on the interfacial properties Evolution during testing:  Plasticity is “homogeneous” up to 90% load at least => most of the stress-strain curve can be used for characterization  Failure in the last 15 seconds of the test: concentration of deformations in a corner & on the interface crack propagation: 1 crack on each interface (A), 1 single crack (B) AB

9. Characterization: 3D FE modelling Inside Outside 3D model: better accuracy & numerical stability, but resolution time x 2. Average Strain: 2% Max Strain: 10%

10. Plasticity evolution

11. Characterization: identification ~1h / 40 FE solutions to identify the material properties, parameters: E, yield stress, hardening, exp. Hardening rate Accuracy: max error +/-4% !!

12. Identification results: constraining effects 1B 2A 3A4B

13. Constitutive stress-strain curves

14. Next steps Testing:  0.5 mm & 0.2 mm joints  Reinforced solder joints  Split testing in 2 procedures: A simple one to compare materials A complete test for characterization Developpments  Bulk solder specimen (FEM =>Design =>production)  A better test specimen for joints ? Shear test (Nokia)? Tensile test ?