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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Reliability Assessment of Ion Contamination Residues on Printed Circuit Board

Nguyen, Minh Tam Tran 01 January 2013 (has links)
Ion contaminants from Printed Circuit Board (PCB) assembly processes pose a high reliability risk because they result in damaged circuits. Therefore, it is essential to understand the level of ionic species on the electronic circuitry as well as the reliability risks caused by these contaminants. There are a number of approaches available in the industry to assess the reliability risks ; for example, the water drop test (WDT) is one of the techniques used to determine the propensity of an ionic contaminant to cause electrical short failures by dendrite formation. The objective of this research is to determine the time to cause the failures, known as electrochemical migration (ECM) failures. A test vehicle was developed for the WDT to obtain the time to cause ECM failure in presence of different anions. The time to form dendritic bridges that cause short circuits was determined as a function of the different anions and the spacings between PCB pads. The experimental method involved dispensing aqueous solutions containing common inorganic and organic acid anions onto test vehicles, applying electrical bias voltages and measuring the time to form dendrites. Specially designed test structures cells were created to contain the test solutions. At each of the test cells, a cavity held the solution and constant current was applied through different metal geometries. To be representative of popular board finishes, test vehicle boards incorporated both Sn-Pb Hot Air Soldering Level (HASL) and Pb free HASL surface finishes.

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