Accession Number : ADA499783


Title :   Microstructure-Evolution and Reliability Assessment Tool for Lead-Free Component Insertion in Army Electronics


Descriptive Note : Final rept. 1 Aug 2006-31 Jul 2008


Corporate Author : GEORGIA INST OF TECH ATLANTA OFFICE OF CONTRACT ADMINISTATION


Personal Author(s) : Tunga, Krishna ; Sitaraman, Suresh K


Full Text : https://apps.dtic.mil/dtic/tr/fulltext/u2/a499783.pdf


Report Date : Oct 2008


Pagination or Media Count : 181


Abstract : This work aims to understand the reliability of Sn-Ag-Cu solder interconnects used in plastic ball grid array (PBGA) packages using microstructure evolution, laser moire interferometry and finite-element modeling. A particle coarsening based microstructure evolution of the solder joint material during thermal excursions was studied for extended periods of time lasting for several months. The microstructure evolution and particle coarsening was quantified, and acceleration factors were determined between long-term field-use conditions and accelerated thermal cycling (ATC) conditions for PBGA packages with different form factors and for two different lead-free solder alloys. A new technique using laser moire interferometry was developed to assess the deformation behavior of Sn-Ag-Cu based solder joints during thermal excursions. This technique can used to estimate the fatigue life of solder joints quickly in a matter of few days instead of months and can be extended to cover a wide range of temperature regimes. Finite-element analysis (FEA) in conjunction with experimental data from the ATC for different lead-free PBGA packages was used to develop a fatigue life model that can be used to predict solder joint fatigue life for any PBGA package. The proposed model will be able to predict the mean number of cycles required for crack initiation and crack growth rate in a solder joint.


Descriptors :   *ELECTRONICS , *MICROSTRUCTURE , *ARMY EQUIPMENT , *SOLDERED JOINTS , LASERS , RELIABILITY , SOFTWARE TOOLS , INTERFEROMETRY , FATIGUE LIFE , ACCELERATED TESTING , MOIRE EFFECTS , FINITE ELEMENT ANALYSIS , CRACK PROPAGATION


Subject Categories : Inorganic Chemistry
      Electrical and Electronic Equipment
      Properties of Metals and Alloys
      Logistics, Military Facilities and Supplies


Distribution Statement : APPROVED FOR PUBLIC RELEASE