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A Liquid Crystal Display Block for Ball Grid Array Socket Solder Joint Detection at the Automated Optical Inspection

IP.com Disclosure Number: IPCOM000020320D
Publication Date: 2003-Nov-12
Document File: 2 page(s) / 57K

Publishing Venue

The IP.com Prior Art Database

Abstract

Disclosed is a method that uses a Liquid Crystal Display (LCD) block to detect Ball Grid Array (BGA) socket solder joints at the Automated Optical Inspection (AOI) machine. Benefits include simplifying In-Circuit Test (ICT) development and fixture design, and transferring BGA socket testing to the AOI machine.

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A Liquid Crystal Display Block for Ball Grid Array Socket Solder Joint Detection at the Automated Optical Inspection

Disclosed is a method that uses a Liquid Crystal Display (LCD) block to detect Ball Grid Array (BGA) socket solder joints at the Automated Optical Inspection (AOI) machine. Benefits include simplifying In-Circuit Test (ICT) development and fixture design, and transferring BGA socket testing to the AOI machine.

Background

Most socket/connector mounting has changed from through-board pins to surface mount BGA; however, visual inspection of the BGA solder joints is not possible. Open solder joints on any of the signal and power pins may result in board malfunctions.

Through Connector Testing (TCT) with the FET or B-Scan modules is normally used for solder joints detection at the ICT; however, the test solution requires a longer test development time. Furthermore, power and analog pins can not be covered with B-Scan test. An alternative is to use the Automated X-ray Inspection (AXI) machine to inspect BGA socket.

General Description

The disclosed method uses a block which consists of LCD cells that power up by battery or solar modules. Each LCD cell is connected to individual balls on the block that match the BGA socket (see Figure 1). One ball in the block is reserved as the power pin. During AOI, the LCD block is inserted into the BGA socket. All BGA socket test points are then shorted together by using a conductive layer (e.g. foam or tape); the test points bec...