The present inventions relate to testing interconnections, such as solder joints, to detect defects that may negatively affect the integrity of a joint, and more specifically to dye-based circuit mount testing of solder joints that connect packaged semiconductors to a printed circuit board (PCB) or other substrate.
A semiconductor package assembly, also called a package, is a carrier for one or more integrated circuits. A package may provide leads, pins, and/or other structures to permit electrical, electronic, and/or mechanical interconnections between the packaged integrated circuit and the supporting PCB or other substrate. A surface-mount component (SMC) is a type of package that may be mounted directly to the surface of a substrate, for example, by soldering its leads and/or pins to the PCB. A ball-grid array (BGA) is a type of SMC that replaces the leads and pins with a grid of solder balls placed on the bottom of the package and held in place, for example, by a flux until soldered. BGA packaging enables a high density of solder-joint connections between the package and the substrate. However, a solder-joint connection may exhibit defects, such as cracks, separations, and/or voids, that may negatively affect the electrical, electronic, and/or mechanical properties of the joint.