A Comprehensive Test Method for Bridging the Gap between Product and Board Level Drop Tests

Abstract

devices, it is also very useful to be able to estimate the life of Due to rapid and continual changes in the components and solder joints under actual usage conditions designs of portable electronic devices, it is essential to have Test methods for assessing the drop impact reliability of the ability to perform quick, cost-effective and accurate solder joints are commonly performed at either the component assessments of the drop impact performance of component level or the board level. In component-level tests -typically interconnections for portable applications. In order to ball shear -loads are applied directly to the solder bumps understand the phenomena of solder joint fatigue under mounted on a package substrate. In board-level tests, loads are impact-induced PCB bending, a tester was developed applied directly to a PCB assembly, which indirectly induces specifically for applying high bending strains at high strain stresses in the solder joints between the component and the rates to a PCB assembly. Fatigue characteristics of solder PCB. joints were determined for various PCB strains, allowing the Much effort has been dedicated to developing a construction of fatigue E-N (strain vs. cycles-to-failure) component-level test method which can assess drop impact curves. Fatigue data was also generated for several bending performance. The earliest reported work on component-level frequencies in a study of the effect of strain rate on drop testing was by Shoji et. al.[6] who used a miniature pendulum impact performance. Higher bending frequencies were found tester to determine the fracture energy of solder joints under to reduce fatigue life. A comprehensive test method would high-speed shear. Since then, more sophisticated tools for also have to be capable of applying variable loading levels in high-speed ball shear have been developed, including order to replicate the complex loading spectrums seen in pendulum testing [8], drop shear [9], and motorized or springactual product drops. A variable amplitude study is presented, driven shear with force/displacement measurement [10-1 1].where crack propagation tracking shows the effect of changes High-speed ball pull studies have also been performed, to a in load levels on the crack growth rate. Finally, a study on the lesser degree [10]. The majority of component-level studies effect of low temperatures on drop impact reliability is have focused on a qualitative approach of correlating shear presented, where fatigue characteristics were obtained using failure modes (e.g. brittle or ductile fracture) with board-level the bend tester fitted with a cold temperature chamber.drop impact performance. However, quantitative measurements of shear fracture strength and fracture energy Introduction were reported to be insensitive to drop impact performance As portable electronic devices (e.g. mobile phones, MP3 [12]. Difficulties in quantitative correlations are due to 1) players) are susceptible to accidental drops in everydaybuse, an significant differences in the solder joint ...