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TOOL AND PROCESS FOR BALL GRID ARRAY (BGA) SOLDER JOINT FAILURE ANALYSIS

IP.com Disclosure Number: IPCOM000008424D
Original Publication Date: 1997-Dec-01
Included in the Prior Art Database: 2002-Jun-13
Document File: 3 page(s) / 124K

Publishing Venue

Motorola

Related People

Joseph Gillette: AUTHOR [+5]

Abstract

The examination of cracked solder joints in BGAs is difftcult since the joints are not directly visible as with leaded components, but rather are hidden beneath the carrier. Therefore, the BGA must be removed to analyze the solder joint fracture surfaces. Removing the BGA is a destructive proce- dure in which the chip and/or printed circuit board (PCB) is damaged and scrapped after analysis. The preservation of valuable solder joint analysis infor- mation during BGA removal, without destroying the component or printed circuit board, can be attained with this invention.

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MOTOROLA Technical Developments

TOOL AND PROCESS FOR BALL GRID ARRAY (BGA) SOLDER JOINT FAILURE ANALYSIS

by Joseph Gillette, Kingshuk Banerji, Edwin Bradley, Jesse Galloway and Pradeep Lall

INTRODUCTION

  The examination of cracked solder joints in BGAs is difftcult since the joints are not directly visible as with leaded components, but rather are hidden beneath the carrier. Therefore, the BGA must be removed to analyze the solder joint fracture surfaces. Removing the BGA is a destructive proce- dure in which the chip and/or printed circuit board (PCB) is damaged and scrapped after analysis. The preservation of valuable solder joint analysis infor- mation during BGA removal, without destroying the component or printed circuit board, can be attained with this invention.

DESCRIPTION

  The tool, shown in Figure I, utilizes a constant load which is converted into a torque via a moment arm and transferred to a pin-stud glued to the BGA as in Figure 2. The PCB is supported vertically along two edges in v-grooves. A v-groove is used to support PCBs of various thicknesses. The v-groove is machined into a block with a dovetail. This dove- tail rides in a slot in the base of the fixture to accommodate various sized PCBs and to assist in

aligning the BGA with the moment arm support. The moment arm is I2 inches in length and of rectangular cross-section. Eleven u-shaped slots, to support a hanger and weight, are machined into the arm so that numerous torque levels can be used for removal. A cylindrical boss, with a drilled hole, is welded to the arm. The pin-stud, which is glued to the BGA, is inserted into the drilled hole of the cylindrical boss. A set screw transfers the load from the weight hung on the moment arm to the pin-stud and BGA. Support for the moment arm, which eliminates transferring bending loads to the board and solder joints, is provided by a pillow block which houses the cylindrical boss of the moment arm. The pillow block rides on two verticle, parallel shafts that are mounted in the base of the fixture. This allows for vertical translation of the moment arm relative to the PCB s...