Abstract: A flexible circuit such as a membrane probe (10) is made by forming a trench (50, 60) in the upper surface (39) of a polyimide substrate (38) with a trench base (52, 62) spaced below the upper surface. The trench has an end wall (54, 64) ramped at an obtuse angle to the substrate upper surface and the trench base. A conductive layer deposited on the upper surface is patterned to form a line trace (44, 46) extending continuously over the substrate upper surface, down the ramped end wall and along the trench base, to contact a ground plane or form a distributed capacitance. An excimer laser is used, at a wavelength of 308 nm., an energy density less than 0.54 J./cm.sup.2 (preferably 0.18 to 0.35 J./cm.sup.2), and a pulse frequency of about 100 Hz., to ablate successive incremental thicknesses (80) of polyimide from the substrate in sweeps of depthwise decreasing length.

Abstract: A flexible circuit such as a membrane probe (10) is made by forming a trench (50, 60) in the upper surface (39) of a polyimide substrate (38) with a trench base (52, 62) spaced below the upper surface. The trench has an end wall (54, 64) ramped at an obtuse angle to the substrate upper surface and the trench base. A conductive layer deposited on the upper surface is patterned to form a line trace (44, 46) extending continuously over the substrate upper surface, down the ramped end wall and along the trench base, to contact a ground plane or form a distributed capacitance. An excimer laser is used, at a wavelength of 308 nm., an energy density less than 0.54 J./cm.sup.2 (preferably 0.18 to 0.35 J./cm.sup.2), and a pulse frequency of about 100 Hz., to ablate successive incremental thicknesses (80) of polyimide from the substrate in sweeps of depthwise decreasing length.

Abstract: A new and improved method for profiling wafers, and for uniquely identifying the dies formed thereon, wherein the method includes the step of locating a set of reference points along the periphery of the wafer, relative to a predetermined coordinate system. Next, the equation of a hypothetical circle which substantially contours the periphery of the wafer, and which passes through the reference points, is defined. The coordinates of the center of the hypothetical circle, as well as the coordinates of an arbitrary reference die on the wafer, are then derived from the equation of the hypothetical circle. Subsequently, the entire surface of the wafer is mapped relative to the center or to the reference die, by utilizing predetermined stepping dimensions.