Tweezer semiconductor die attach method and apparatus

摘要

A method and apparatus for attaching semiconductor dice to substrates includes a novel die-grasping apparatus and technique which employs a tweezer-like clamping device which has one fixed leg. The second leg of the clamping device is movable laterally towards the fixed leg by means of a linear actuator coupled to the movable leg through a spring. Lateral spacing between the linear actuator and the movable leg is adjustable, allowing the spring to be prestressed to a precisely adjustable value, thereby resulting in a precisely pre-adjustable side-gripping force on the lateral sides of a semiconductor chip or die, ensuring that the fragile die will not be broken by the grasping action. The preferred embodiment employs a micro-manipulator to precisely position a die in place on a molten solder pre-form on a substrate, and a vacuum probe for first placing the pre-form on the substrate. Also included in the preferred embodiment is a load cell responsive to a pre-determined normal force on a die in initiating lateral oscillation of the die in contact with the liquified pre-form. This "scrubbing" action improving the quality of the bond formed between the die and substrate when the solder re-solidifies.