An X-Ray Imaging-Based Layer Alignment and Tape Deformation Inspection System for Multilayer Ceramic Circuit Boards

Advances in conductor patterning and via preparation techniques have facilitated a continuous increase in the circuit packaging density of ceramic multilayer substrates. A decrease in feature size combined with the trend toward constantly increasing the processed panel size is placing extremely high demands for layer-to-layer alignment as well as ceramic green tape stability. This paper describes the main mechanisms contributing to layer-to-layer alignment errors in the ceramic tape alignment and stacking process and introduces a simple, nondestructive, X-ray imaging-based method for measuring alignment error in a ceramic multilayer substrate. A low-temperature cofired ceramic (LTCC) test panel was manufactured and analyzed using the introduced X-ray inspection method. In order to define the error caused by tape alignment and stacking as well as tape deformation, the alignment error between the layers was calculated over the whole panel area. The specific area of an LTCC panel that meets the required alignment tolerances can be identified from the calculated results.