Adhesion of silver thick-film conductors to alumina substrates was studied by a solderless testing meth od, in wh ich al um ina substrates were bonded with a silver thick-fi Im and pul led vertically under a constant strain rate to fracture. The fracture behaviour was studied on thick films prepared under different conditions, and the effect of microstructure on the adhesion strength was studied. A new parameter has been introduced for evaluating the resistance to crack propagation. Hence, microstructural requirements for high adhesion strength thick films have been proposed. The adhesion strength data of silver thick films have been best described by a log-normal distribution function.