Patent ID: 6840667

Claim:
A method for inspecting and detecting defects in an object, said method comprising: providing a thermal stimulation to a first side of said object; capturing at least one infrared image of said object on a second side to record a change in infrared radiation from said second side resulting from said thermal stimulation; comparing said change in infrared radiation within a region on said second side of said object to a reference; and determining whether said object comprises any defects, wherein said providing a thermal stimulation comprises: using a focused laser beam to inject heat on a point in close proximity to said solder junctions; selecting a desired thermal stimulation energy for each of said at least one point on said object; selectively stepping said focused laser beam across said solder junctions while ensuring sufficient time for dissipation of heat before a neighboring solder junction is thermally stimulated; determining an area S on at least one of said objects around each of said locations disturbed by thermal propagation resulting from injections of said desired thermal injection energy and a time T required for dissipation of said desired thermal injection energy to a non-disturbing level, said desired thermal injection energy and said locations resulting in overlap of said area S associated with at least some neighboring ones of said locations; and determining from said locations, said area S, and said time T, an injection sequence for injecting said desired thermal injection energy in said objects at said locations while imaging thermal propagation of said desired thermal injection energy in said object without disturbance of thermal propagation from neighboring one of said locations.