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Proceedings Paper

Laser Inspection Or Soldered Connections
Author(s): Richard I. Alper; Alan C. Traub
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Paper Abstract

A sensitive infrared detection system monitors the slight warming and cooling of a solder joint on a PWB in response to a focused laser beam pulse lasting for 30 milliseconds. Heating and cooling rates depend on the surface finish of the solder and also upon its interr.1 features. Joints which are alike show similar heating rates; defects behave differently and are flagged as showing abnormal thermal signatures Defects include surface voids, cold solder, insufficient or missing solder, residual solder flux, contamination and large subsurface voids. Solder bridges can usually be found by targeting at suspected bridge locations. Feed-through joints at DIPs and lap joints at flat-pack ICs are readily inspected by this method. By use of computer-controlled tiltable optics, access is had to the "harder to see" joints such as at leadless chip carriers and other surface mounts. Inspection rates can be up to 10 joints per second.

Paper Details

Date Published: 7 July 1986
PDF: 8 pages
Proc. SPIE 0611, Laser Processing of Semiconductors & Hybrids, (7 July 1986); doi: 10.1117/12.956415
Show Author Affiliations
Richard I. Alper, Vanzetti Systems, Inc. (United States)
Alan C. Traub, Vanzetti Systems, Inc. (United States)

Published in SPIE Proceedings Vol. 0611:
Laser Processing of Semiconductors & Hybrids
Edward J. Swenson, Editor(s)

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