An electrolyte is employed to test for defects in bare printed circuit boards. A bare board under test is placed in a conductive tank and immersed in an electrolyte. A probe is then used to contact a pad of a net to be tested on the board. The electrical resistance is then measured across the net and the electrolyte, the magnitude of the resistance being related to the number of pads actually connected to the net. The measurement thus provides an indication of whether the correct number of pads have been detected. Defects on the board, such as unintended short circuits and open circuits, cause the number of pads detected to be different from the expected value, thereby affecting the measured resistance.

Systems and methods for detecting and eliminating latent and existing short circuit current paths through photovoltaic devices of the type including at least one semiconductor region overlying a substrate and a layer of conductive light transmissive material overlying the at least one semiconductor region are disclosed. The latent paths are first converted to existing short circuit current paths by applying a bias voltage to the devices. The short circuit current paths which are eliminated extend through the at least one semiconductor region from the substrate to the layer of conductive light transmissive material. The resistivity of the short circuit current paths is increased substantially at the interface between the conductive light transmissive material and the semiconductor region by isolating electrically the conductive light transmissive material from the short circuit current path. The isolation can be provided by removing the transparent conductive material from electrical contact or connection with the short circuit current path. The isolation also can be provided by depositing a body of insulating material onto the semiconductor region over an area including a short circuit current path prior to the deposition of the conductive light transmissive material. Further, the short circuit current path can be detected and located by applying a voltage to discrete areas of the device through a conductive solution which path then can be eliminated as described above.

An apparatus and method for a cleaning process control is disclosed. The apparatus includes two parallel plates of glass that have a plurality of shims positioned therebetween and a means for clamping these plates of glass firmly against the shims. A contaminant is positioned between the plates of glass and the apparatus is cleaned using a selected cleaning process. The apparatus can then be inspected to determine the effectiveness of a particular cleaning process by peering through the transparent glass plates to inspect for any remaining contaminant. The apparatus can then be cleaned more extensively and used again to check a different cleaning process.

A method and device are provided for determining a parameter for the reproducible production of raised contact metallizations (24, 25) on terminal areas of a substrate. Metallization material is deposited in a metallization bath. A test substrate is employed having at least two terminal areas adjacent at a defined spacing. The substrate is introduced into the metallization bath (10) and the parameter is determined from the variation in an electrical quantity as a consequence of an electrical contact resulting to from the deposition of the metallization material for building up the contact metallizations (24, 25) on the adjacent terminal areas.

An improved method is provided for the visual inspection of printed circuit boards to determine the continuity or discontinuity of the circuits. In the method the circuit boards are treated in an electrolytic bath to cause an electrochemical change in the color of the continuous circuits versus the discontinuous circuits.