Electrical characterization of laser machined and metallized vias in AlN with thick film interconnect

The objective of this work was to develop a procedure to ensure good electrical interconnection between the thick film conductor pads and the metal coated walls of via holes. The via metallization technique involves excimer laser ablation of aluminum nitride (AlN) substrate and either an aluminum or copper metal sheet adhesively attached to the substrate. Ablated metal from the attached metal sheet deposits on the interior walls of the laser machined via making a conductive pathway through the via. Resistance was measured for vias processed in several different atmospheres, and the cross-sections of the vias were analyzed using scanning electron microscopy (SEM). Energy dispersive analysis of X-rays (EDAX) was performed at various points in the cross section to determine the elements present.