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ZERO ANGLE PERIMETER LIGHTING FOR INSPECTING BALL GRID ARRAY SOLDER SPHERES

IP.com Disclosure Number: IPCOM000007410D
Original Publication Date: 1995-Mar-01
Included in the Prior Art Database: 2002-Mar-22
Document File: 1 page(s) / 88K

Publishing Venue

Motorola

Related People

Tom Kirby: AUTHOR

Abstract

The implementation of Ball Grid Array (BGA) sphere leaves a dark "hole" (see Figure 3 and 4). IC packages presents a machine vision challenge dur- This lighting technique lends itself well to full array ing packaging and placement of the part. Taking an and singulated part inspection. accurate count of the balls is critical at both the solder sphere attach process and the automated pick and place stage. In an effort to provide reliable inspec- Fla. 1 Fiber-oDtic Liaht Bar tion of BGA packages, this ze;o-angle lighting tech- nique was developed.

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MOTOROLA Technical Developments Volume 24 March 1995

ZERO ANGLE PERIMETER LIGHTING FOR INSPECTING BALL GRID ARRAY SOLDER SPHERES

by Tom Kirby

  The implementation of Ball Grid Array (BGA) sphere leaves a dark "hole" (see Figure 3 and 4). IC packages presents a machine vision challenge dur- This lighting technique lends itself well to full array ing packaging and placement of the part. Taking an and singulated part inspection.
accurate count of the balls is critical at both the
solder sphere attach process and the automated pick
and place stage. In an effort to provide reliable inspec- Fla. 1 Fiber-oDtic Liaht Bar
tion of BGA packages, this ze;o-angle lighting tech-
nique was developed.

  The basic approach is to form a "sheet" of light approximately 10 mils thick, which contains the entire grid to be inspected. This is accomplished using four custom sized fiber-optic light bars (available from Fostec Figure 1) to form a perimeter. Light is reflected off the curved surface of each ball, while the carrier surface remains dark. Each solder sphere appears as a tiny "light bulb" in the image, while a missing

Fig. 2 Pick and Place Robot Inspection Fig. 3 Illustrated Fixed Camera Images

Fig. 4 Full Array InspectIon

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0 Motorda. Inc. ,995

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