| 摘要 |
<p>A multilayer attach (21) including alternating layer of solder (204, 208, 212) and barrier metals (206, 210) is used to replace the conventional solder bumps or balls in flip-chip bonding. The thin solder layers undergo grain boundary sliding deformation rather than matrix deformation when the attach is subjected to lateral shear forces as a result of the differential thermal expansion of the chip (20) and the substrate (22). Grain boundary sliding deformation is relatively damage-free as compared to matrix deformation, which generates voids, cracks and fractures in the attach, ultimately leading to a defective electrical or thermal connection. In one embodiment, the attach includes three solder layers each of which is no more than 50 νm thick.</p> |
