Thermo-mechanical deformations of microstructures in a surface laminar circuit (SLC) substrate are quantified by microscopic moire´ interferometry. Two specimens are analyzed; a bare SLC substrate and a flip chip package assembly. The specimens are subjected to a uniform thermal loading of ΔT=−70°C and the microscopic displacement fields are documented at the identical region of interest. The nano-scale displacement sensitivity and the microscopic spatial resolution obtained from the experiments provide a faithful account of the complex deformation of the surface laminar layer and the embedded microstructures. The displacement fields are analyzed to produce the deformed configuration of the surface laminar layer and the strain distributions in the microstructures. The high modulus of underfill produces a strong coupling between the chip and the surface laminar layer, which produces a DNP-dependent shear deformation of the layer. The effect of the underfill on the deformation of the microstructures is investigated and its implications on the package reliability are discussed. [S1043-7398(00)01304-9]

Issue Section:
Technical Papers
Keywords:
plastic packaging, flip-chip devices, micromechanics, circuit reliability, shear deformation, thermal stresses, light interferometry, Surface Laminar Circuit, Flip Chip, Underfill, Microscopic Moire´ Interferometry, Photosensitive Dielectric Layer, Solder Resist Mask, Metal Via
Topics:
Circuits, Deformation, Displacement, Flip-chip devices, Flip-chip packages, Interferometry, Flip-chip assemblies, Metals, Shear deformation, Reliability, Flip-chip, Solder masks, Manufacturing, Shear (Mechanics)
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