Challenges for the prediction of solder joint life in long term vibration

Abstract

In the absence of manufacturing defects the ultimate life of a microelectronics assembly in long-term vibration is likely to be limited by solder joint fatigue. So far relatively limited efforts have been dedicated to the quantitative prediction of this life. However, even day to day 'engineering tests' may not be very useful if they do not offer at least a ranking of alternative materials, designs or processes in terms of performance in service.

A Mechanistic Thermal Fatigue Model for SnAgCu Solder Joints

“…Isothermal cycling does not lead to extensive recrystallization, and failure does eventually occur by the growth of a crack through the lattice. 64,65 The same mechanism is also active in thermal cycling, leading to an almost immediate initiation of a transgranular crack. 11 However, the dominant mechanism is the formation and ongoing rotation of new grains leading to ever greater misorientation and eventually crack growth.…”

“…24,26 The transgranular crack growth mechanism may involve local recrystallization near the crack tip, but from a modeling perspective, at least it is completely different. In isothermal cycling, failure by transgranular crack growth can be predicted based on the total inelastic work per cycle, 64,65 whereas intergranular crack growth in thermal cycling clearly cannot. The very different dependencies on cycling parameters may explain why one thermal cycling test under conditions approaching those typical of long-term service led to major recrystallization, 22 while another did not.…”

“…In the case of isothermal cycling, say in vibration, the resulting accumulation of damage and eventual failure cannot be predicted, even approximately, based on results of fixed amplitude cycling tests alone. [63][64][65] That is a result of longterm effects ('memory') of amplitude on the material's properties. Ignoring these leads to overestimates of life in service.…”

Survey on Fatigue Life Prediction of BGA Solder Joints

“…If the temperature distribution inside the chip package is not uniform, the signal transmission characteristics of the chip will be influenced, thereby affecting the life and reliability of the electronic device. Additionally, because of the differences in the thermal expansion coefficient between chip packaging materials [31][32][33][34][35][36][37][38][39][40][41][42][43][44], different materials have different degrees of thermal expansion and contraction under the influence of temperature. This results in additional stress and strain inside the electronic components, especially inside solder joints.…”