### Abstract

Creep data for a eutectic tin-silver alloy at temperatures between 298 K and 398 K have been analyzed using the modified theta-projection concept, instead of the steady-state creep constitutive equation in the following formula: ε_{cr} = A (1 - exp(-αt)} + B (exp(αt) - 1}, where A, B, and a are constants to be experimentally determined. The equation describes well the creep curves of the eutectic tin-silver alloy up to the tertiary stage. All constants exhibited power law relationships with the applied stress. The rate constant, α, has a high stress exponent, which is attributed to dispersion strengthening. The rate constant a and the strain factor B only showed temperature dependence, while the strain factor A was independent of temperature. The activation energy for α was 65 kJ/mol at high stresses and 90 kJ/mol at low stresses. The energies suggest that the dislocation pipe diffusion and the lattice diffusion are predominant at high stresses and low stresses, respectively.

Original language | English |
---|---|

Pages (from-to) | 1398-1402 |

Number of pages | 5 |

Journal | Journal of Electronic Materials |

Volume | 32 |

Issue number | 12 |

Publication status | Published - 2003 Dec |

Externally published | Yes |

### Fingerprint

### Keywords

- θ projection
- Constitutive equation
- Creep
- Lead-free solder
- Nonsteady state
- Sn-3.5Ag

### ASJC Scopus subject areas

- Electrical and Electronic Engineering
- Electronic, Optical and Magnetic Materials
- Materials Science(all)
- Physics and Astronomy (miscellaneous)

### Cite this

*Journal of Electronic Materials*,

*32*(12), 1398-1402.

**The Constitutive Creep Equation for a Eutectic Sn-Ag Alloy Using the Modified Theta-Projection Concept.** / Kariya, Yoshiharu; Otsuka, Masahisa; Plumbridge, William J.

Research output: Contribution to journal › Article

*Journal of Electronic Materials*, vol. 32, no. 12, pp. 1398-1402.

}

TY - JOUR

T1 - The Constitutive Creep Equation for a Eutectic Sn-Ag Alloy Using the Modified Theta-Projection Concept

AU - Kariya, Yoshiharu

AU - Otsuka, Masahisa

AU - Plumbridge, William J.

PY - 2003/12

Y1 - 2003/12

N2 - Creep data for a eutectic tin-silver alloy at temperatures between 298 K and 398 K have been analyzed using the modified theta-projection concept, instead of the steady-state creep constitutive equation in the following formula: εcr = A (1 - exp(-αt)} + B (exp(αt) - 1}, where A, B, and a are constants to be experimentally determined. The equation describes well the creep curves of the eutectic tin-silver alloy up to the tertiary stage. All constants exhibited power law relationships with the applied stress. The rate constant, α, has a high stress exponent, which is attributed to dispersion strengthening. The rate constant a and the strain factor B only showed temperature dependence, while the strain factor A was independent of temperature. The activation energy for α was 65 kJ/mol at high stresses and 90 kJ/mol at low stresses. The energies suggest that the dislocation pipe diffusion and the lattice diffusion are predominant at high stresses and low stresses, respectively.

AB - Creep data for a eutectic tin-silver alloy at temperatures between 298 K and 398 K have been analyzed using the modified theta-projection concept, instead of the steady-state creep constitutive equation in the following formula: εcr = A (1 - exp(-αt)} + B (exp(αt) - 1}, where A, B, and a are constants to be experimentally determined. The equation describes well the creep curves of the eutectic tin-silver alloy up to the tertiary stage. All constants exhibited power law relationships with the applied stress. The rate constant, α, has a high stress exponent, which is attributed to dispersion strengthening. The rate constant a and the strain factor B only showed temperature dependence, while the strain factor A was independent of temperature. The activation energy for α was 65 kJ/mol at high stresses and 90 kJ/mol at low stresses. The energies suggest that the dislocation pipe diffusion and the lattice diffusion are predominant at high stresses and low stresses, respectively.

KW - θ projection

KW - Constitutive equation

KW - Creep

KW - Lead-free solder

KW - Nonsteady state

KW - Sn-3.5Ag

UR - http://www.scopus.com/inward/record.url?scp=0942288661&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=0942288661&partnerID=8YFLogxK

M3 - Article

AN - SCOPUS:0942288661

VL - 32

SP - 1398

EP - 1402

JO - Journal of Electronic Materials

JF - Journal of Electronic Materials

SN - 0361-5235

IS - 12

ER -