Details

Autor(en) / Beteiligte

• Bieler, Thomas R.
• Lee, Tae-kyu
• Liu, Kuo-Chuan

Titel

Methodology for Analyzing Strain States During In Situ Thermomechanical Cycling in Individual Lead-Free Solder Joints Using Synchrotron Radiation

Ist Teil von

• Journal of electronic materials, 2009-12, Vol.38 (12), p.2712-2719

Ort / Verlag

Boston: Springer US

Erscheinungsjahr

2009

Quelle

Alma/SFX Local Collection

Beschreibungen/Notizen

• To examine how a lead-free solder joint deforms in a thermal cycling environment, both the elastic and plastic stress and strain behavior must be understood. Methods to identify evolution of the internal strain (stress) state during thermal cycling are described. A slice of a package containing a single row of solder joints was thermally cycled from 0°C to 100°C with a period of about 1 h with concurrent acquisition of transmission Laue patterns using synchrotron radiation. These results indicated that most joints are single crystals, with some being multicrystals with no more than a few Sn grain orientations. Laue patterns were analyzed to estimate local strains in different crystal directions at different temperatures during a thermal cycle. While the strains perpendicular to various crystal planes all vary in a similar way, the magnitude of strain varies. The specimens were subsequently given several hundred additional thermal cycles and measured again to assess changes in the crystal orientations. These results show that modest changes in crystal orientations occur during thermal cycling.