SMTA International Conference Proceedings


Authors: Thomas A. Woodrow, Ph.D.
Company: Boeing Phantom Works
Date Published: 9/25/2005   Conference: SMTA International

Abstract: Vibration testing was conducted by Boeing Phantom Works (Seattle) for the Joint Council on Aging Aircraft/Joint Group on Pollution Prevention (JCAA/JGPP) No-Lead Solder Project. The JCAA/JG-PP Consortium is the first group to test the reliability of leadfree solder joints against the requirements of the aerospace/military community. A complete modal analysis was conducted on one test vehicle (the pathfinder PWA) using a laser vibrometer system. This system measured velocities, accelerations and displacements of the PWA during the vibration test.

The laser vibrometer data was used to determine the resonant frequencies of the pathfinder PWA and the actual deflection shapes of the PWA during test. In addition, the strains generated during a 1 G sine dwell were calculated for 1189 points on the pathfinder PWA. After completion of the modal analysis, thirty test vehicles (in two batches of 15 test vehicles each) were subjected to the vibration test conditions. The input power spectral density was increased during the test at 60 minute intervals in an effort to fail as many components as possible within the time allotted for the test.

The solder joints on the components were electrically monitored using event detectors and any solder joint failures were recorded on a Labview-based data collection system. The time to failure of a given component attached with SnPb solder was then compared to the time to failure of the same component attached with lead-free solders. After completion of the testing, all of the test vehicles were visually inspected. Broken component leads and other unwanted failure modes were documented.

Key words: Vibration, lead-free solders, reliability

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