A displacement-error monitor of a multi-layer LTCC module

A displacement error of each sheet of a multi-layer low temperature co-fired ceramic (LTCC) module is one of the critical issues to obtain high yield production. This paper introduces an embedded passive component that monitors displacement error of a certain layer by measuring its frequency response. Also, the displacement-error monitor (DEM) is so designed that the displacement of a certain direction cause significant change of the response but the opposite direction as well as the perpendicular one does not. Embedding the DEMs in sheets of LTCC, we can monitor the error and can feedback to the process of fabrication to reduce discarded products. Two lots of LTCC modules were fabricated and tested. Displacements were monitored by the DEM and also were inspected directly by cutting off at a certain pattern. The measured results agree well with the displacements inspected at the cross section.