Numerical Simulation
Deformation analysis of electronic assemblies predicts the out-of-plane distortion that occurs during thermal processing cycles. Within this manufacturing domain, warpage modeling computes the structural displacement of printed circuit boards or multi-material packages subjected to reflow temperatures. This simulation identifies potential geometry issues before physical tooling is created.
Deformation Mechanism
Differential thermal contraction between the silicon die, adhesive, and substrate drives the bending behavior during the cooling phase. When warpage modeling is performed, the mismatched coefficients of thermal expansion of the joined materials are the primary input variables that determine the magnitude of the displacement.
Parameter Calibration
Accurate calculation of the distorted shape requires the integration of temperature-dependent material behaviors and chemical shrinkage properties. Viscoelastic characteristics of the polymers must be characterized to account for the stress relaxation that occurs at high temperatures. Designers must verify these material parameters against laboratory measurements to ensure the reliability of the simulation.
If these properties are not calibrated correctly, the simulated displacements will deviate from the actual behavior of the cured assembly.
Defect Prevention
The simulated distortion patterns allow manufacturing engineers to adjust the layout of the package to minimize the risk of assembly defects. High warpage can cause solder joint failures, such as open connections or bridging between adjacent contacts. By adjusting the component layout or the substrate thickness, the overall reliability of the finished electronic product is increased.
