Coarsening of the Sn-Pb solder microstructure in constitutive model-based predictions of solder joint thermal mechanical fatigue
An expression for the coarsening rate of the Pb-rich phase particles was determined through isothermal aging experiments and comparative literature data as: {lambda} = {lambda}{sub o} + {l{underscore}brace}[4.10 x 10{sup {minus}5} e{sup {minus}11023/T} + 15.6 x 10{sup {minus}8} e{sup {minus}3123/T} (d{gamma}/dt)]t{r{underscore}brace}{sup 0.256} where {lambda}{sub o} and {lambda} are the initial and final mean Pb-rich particle diameters, respectively (mm); T is temperature (K); t is time (s); and d{gamma}/dt is the strain rate (s{sup {minus}1}). The phase coarsening behavior showed good agreement with previous literature data from isothermal aging experiments. The power-law exponent, p, for the Pb-rich phase size coarsening kinetics: {lambda}{sup p} {minus} {lambda}{sub o}{sup p} {approx} t increased from a value of 3.3 at the low aging temperature regime (70--100 C) to a value of 5.1 at the high temperature regime (135--170 C), suggesting that the number of short-circuit diffusion paths had increased with further aging. This expression provides an important basis for the microstructurally-based, constitutive equation used in the visco-plastic model for TMF in Sn-Pb solder. The revised visco-plastic model was exercised using a through-hole solder joint configuration. Initial data indicate a satisfactory compatibility between the coarsening expression and the constitutive equation.
- Research Organization:
- Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)
- Sponsoring Organization:
- USDOE
- DOE Contract Number:
- AC04-94AL85000
- OSTI ID:
- 20001756
- Journal Information:
- Journal of Electronic Materials, Vol. 28, Issue 11; Conference: InterconnectPACK: Interconnections for Electronic Packaging, San Diego, CA (US), 02/28/1999--03/04/1999; Other Information: PBD: Nov 1999
- Country of Publication:
- United States
- Language:
- English
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