Importance

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Abstract

An array of touch sensors are brought in contact with a ball grid array. A linear actuator moves the array of touch sensors. The position of the linear actuator is known very precisely. As the touch sensors encounter the ball grid array, they provide a signal to a computer system that an element on the ball grid array has been encountered. The computer notes the position of the linear actuator and the particular sensor in the touch sensor array that is providing the signal. Initially, each touch sensor rests against a printed circuit board circuit with a conductive disk connecting the circuit in an unactuated position. In an actuated position, the circuit is broken by the touch sensor being forced away from the printed circuit board by the object encountered. Positive air pressure is provided against one side of the disk to press it against the contact points on the printed circuit board. An alignment plate helps prevent tilting of a touch sensor. A circular cartridge is loaded by a chip handler and multiple array sensors are used to test for board warpage and various ball grid configurations.

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First Claim