Bi-material assembly with a low-modulus-and/or-low-fabrication-temperature bonding material at its ends: optimized stress relief

  • E. Suhir


Simple and physically meaningful predictive analytical models are developed for the assessment of thermal stresses in a ball-grid-array or in a column-grid-array with a low modulus solder material at the peripheral portions of the assembly. It is shown that a significant thermal stress relief can be achieved, if the bonding system is designed in such a way that the interfacial shearing stress at the ends of the high-modulus-and-high-bonding-temperature mid-portion of the assembly at its boundary with the low-modulus-and-low-bonding-temperature peripheral portion is made equal to the stress at the assembly ends. Stress relief as high as 34.3 % can be obtained in the optimized design. If such a design is employed, there is a possibility that no inelastic stresses and strains in the solder joints will occur, and the fatigue life of the vulnerable solder material will be increased dramatically.


Stress Relief Interfacial Stress Interfacial Shearing Stress Bonding Layer Peripheral Portion 
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Copyright information

© Springer Science+Business Media New York 2016

Authors and Affiliations

  1. 1.Portland State UniversityPortlandUSA
  2. 2.ERS Co.Los AltosUSA
  3. 3.Technical UniversityViennaAustria
  4. 4.Ariel UniversityArielIsrael

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