International Business Machines Corporation

John Joseph Garrity

John James Hannah McMorran

Brian L Robertson

Alan P Downie

Peter Gallagher

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.

Enhanced pad design for substrate

A direct chip attach module (DCAM) 10, comprises of one or more electronic components 30, electrically bonded to a printed circuit 40, on a substrate 20. The DCAM 10, is bonded to an electronic circuit assembly by connection pads 50, formed on the edge of the DCAM substrate 10. This enables easy visual inspection of solder joints between the DCAM and the assembly. DCAM substrates 10, are initially formed in a panel form 70, and vias 50, are drilled and filled with electrically conductive media 55, at predetermined connection points. The DCAM 10, is then excised from the parent panel 70, and the cut vias provide connection pads 55, along the edge of the substrate 10.

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Strathclyde, United Kingdom

John Joseph Garrity