Sequential process modeling of SLIM substrate fabrication

Abstract

A parametric process modeling approach has been implemented to simulate the sequential build-up process of a multilayered substrate. Generalized deformation models with element birth and death feature is used to activate and deactivate the material layers to simulate substrate fabrication. Using process models, one can determine the warpage and also axial and interfacial stresses at any intermediate stage in the process. This process-modeling approach is in contrast to the "frozen-view" models employed by many researchers, which are shown to yield overly conservative and sometimes erroneous results, leading to non-optimal design solutions. Residual warpage results are presented for the sequential build-up of a complex multilayered substrate with thin film passives integrated within the HDI (high density interconnect) layers. In addition, a comparison with the results using a frozen-view modeling approach is presented, and an alternate improved substrate processing technique is suggested to eliminate intermediate board warpage for a single-sided multilayer construction prior to polymer deposition.