Automated Optical BGA-Inspection – AUTOBIN

Abstract

Today’s highly complex microelectronic integrated circuits require large numbers of electrical connections for power supply and signal input/ ouput. Ball Grid Arrays (BGA) have found a wide-spread use in microelectronic packaging, as they offer a large number of connections with advantageous electrical and thermal parameters. The quality inspection of printed circuit boards faces difficulties, because the soldering connections of the BGA are hidden under the component and are neither accessible for electronic probing nor for ordinary visual inspection of the quality of the soldered joints. Only quite expensive X-ray systems are applicable, but even these do not reveal all possible types of defect. Visual inspection of soldered joints can be done by applying microendoscopes that can be used to look into the small gap between the component and the electronic board. Such systems are commercially available, but the adjustment of the fiberoptic endoscope and the illumination fibres requires precise manual adjustments. The interpretation of the images is left to the user. The aim of this transfer project is to transfer this approach to an automatic testing equipment. In the SFB 516, a miniaturized optical 3D-sensor has been developed to control microassembly processes. This sensor will be modified and adapted to the task of adjustment of the endoscope relative to the BGA component. A miniaturized pattern projector has to be developed and integrated into the compact housing. The industrial partner will integrate this sensor into an automated optical inspection system and will develop image-processing software to evaluate the soldered joints.