Method for contactless testing of integrated circuit packaging boards under atmospheric conditions.

摘要

For testing the integrity of conducting lines on or in a substrate , the following steps are executed: (I) Selected pads (P21) are irradiated by a focused laser beam so that they are positively charged due to photon-assisted tunneling of electrons from those pads. The charges propagate through existing conductors so that all selected pads (P21) and all pads connected to them (P22) assume a specific voltage. (II) The whole surface is irradiated by a flooding laser beam. Photon-assisted tunneling of electrons will now occur from those pads which were not charged previously (P11, P12). (III) The tunneling electrons excite an electroluminiscent layer whose illumination reveals the spatial distribution of uncharged pads. This method is performed in air under atmospheric conditions and allows completely contactless testing of circuitry to detect line interruptions as well as shortcuts between separate lines. It is suited for surface lines, buried lines, and in particular also for via connections.