Abstract: An electrochemical microsensor package comprises a substrate matrix having a upper non-conductive layer and an adjacent lower non-conductive layer with a conductive trace or pad extending over an area therebetween. The conductive pad has integral therewith a projecting contact button that projects through and below the second non-conductive for making contact with external electrical contacts. A sensor electrode is positioned on the surface of the conductive pad toward the upper non-conductive layer and in electrical contact therewith. A well extends through the upper non-conductive layer to the upper surface of the electrode. The microsensor packages may be produced by electrodeposition of the conductive pad onto a conductive mandrel having depressions to form the contact button.