International Business Machines Corporation

John James Hannah McMorran

John Joseph Garrity

A ball grid array electronic package is attached to a substrate by means of solder balls and solder paste. Connection is made between a contact on the ball grid array and a solder ball by means of a first joining medium, such as a solder paste. Connection is made between a solder ball and a contact arranged on the substrate by means of a second joining medium. The contact arranged on the substrate is substantially quadrilateral in shape, and preferably substantially square in shape. Connection to the substrate, e.g., using round solder balls, is much more easily detected, e.g., by x-ray, than when using round pads, especially those having a smaller diameter than the balls.

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Largs, United Kingdom

John James Hannah McMorran