Abstract: A selective method of etching chromium is described. In the present invention an etching cycle, including etching with a first solution including potassium permanganate and then with a second solution including oxalic acid is defined. Such a cycle will remove a thin layer of chromium and may be required to be performed a plurality of times to complete the etching process.

Abstract: A limitation in the use of ceramic substrates for electronic packaging is that photolithographic processes applied to such substrate surfaces do not give the highest resolution that the process is capable of because of inherent surface topographical variations on the ceramic substrate. A smoothing layer of a dry film glazed photosensitive material, such as RISTON solder mask, is laminated over the substrate surface, exposed with UV and cured. Metal conductor lines are then bonded onto the surface of the solder mask layer.

Abstract: An improved method of forming raised input/output (I/O) terminals on the top surfaces of semiconductor elements of a semiconductor wafer. After via openings are formed through the passivation layer of such elements at locations where the I/O terminals are to be formed, which openings provide access to the metalization layers of the elements photolithographic techniques using a layer of heat resistant photoresist which is laminated to the top surface of the wafer are used to form openings through the photoresist layer to provide access to the metalization layers through the vias. A barrier metal layer is deposited on the exposed surfaces of the photoresist, and the metalization layers, and passivation layer of the elements. The barrier metal layer overlying the photoresist and then the photoresist are stripped from the wafer. The same photolithographic techniques using the same heat resistant photoresist material are used to define openings surrounding the barrier metal lining the via openings.

Abstract: A threshold magnetic switch is described, with adjustable threshold level for varying applications, or for purposes of matching sensitivities of several switches in utilizing apparatus.