ICSR (Soldering and Reliability) Conference Proceedings

Use Of Combination 2d And Ct Scan X-Ray Imaging For Solder Joint Inspection

Authors: Nandu Ranadive
Company: IBM Corporation
Date Published: 5/17/2010   Conference: ICSR (Soldering and Reliability)

Abstract: Connector technology used in the high density printed circuit boards demands high speeds and low signal to noise ratios. In order to improve the connector density, more and more connectors are going surface mount, with very high I/O count. I/O counts in excess of 5000 connections on a single connector site, are not uncommon. In order to provide connections to all the I/O's, the connectors often tend to be dense and have a very high profile. A reliable inspection of these connections is essential to reduce the defect levels and assess the long term reliability of solder joints. A unique combination of conventional 2D X-ray inspection and CT scan (3D reconstruction) is used to inspect such joints. This unique combination has made possible, a reliable inspection of solder joints for defect like shifted connectors leads, low solder volume, solder climb, solder thieving etc. A quick identification of these defects was used to drive process corrective actions and reduce the test down times. This paper discusses the combination techniques and shows various illustrations of defects which are normally difficult to detect.

One great advantage of such a system is the ability to use it as a combination tool, or two stand-alone tools that can be used for various other types of inspections when needed. For instance, a 2D inspection tool was also used to inspect solder joints on standard SMT connectors, pin-thru-hole connections etc, and for analyzing internal component defects. The CT scan could be used for understanding other types of defects, such as, shorts internal to the components, internal structures of circuit boards etc.

Key Words: High density connectors, 2D X-ray inspection, CT scan, solder joint, IPC requirements for solder joints, automation.

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