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24 (07.5.1) |
Evaluating the CAF (conductive anodic filament) resistance of multi-layered PWBs |
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Abstract
Advances in the high-density wiring of electronic parts have been accompanied by insulation degradation stemming from ion migration, creating serious problems. While a great deal of research has been carried out investigating the formation of dendrites, which are one form of ion migration, there has been a noticeable lack of clarification of the role of CAF (conductive anodic filament) formation. As a result, we decided to evaluate the CAF resistance of multi-layered PWBs (printed wiring boards). We investigated the relationship between the shape of the CAF that formed and the behavior of insulation resistance levels during CAF formation. We found that during CAF formation the insulation resistance levels repeatedly dropped temporarily and then recovered. In addition, we observed a substance presumed to be CAF at the sites of probable insulation degradation, and we were able to confirm that this substance occurred along the glass fibers. |
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16 (03.10.1) |
Using the EIS method to analyze the reaction mechanisms of
the ionic migration process in solder materials |
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Abstract
Electrochemical impedance spectroscopy (EIS) is attracting attention as an effective method of
analyzing electrode interfacial reactions. In this method, a minute AC sine wave signal is
overlapped onto a DC signal. The resultant reaction characteristics are then used to analyze the
reaction mechanisms.
For this report, we used the EIS method to analyze the reaction mechanisms of the migration
process in solder materials.
The results of this study indicate that the process of ionic migration (also known as electrochemical
migration) involves a charge transfer process and a mass transfer process. By monitoring changes
in the characteristic values, ionic migration characteristics can be assigned to each type of solder
material and used to predict the likelihood of migration occurrence. |
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12 (01.10.1) |
How impurities affect ionic migration,and how to counter their impact |
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Abstract
The author has studied how impurities adhering to PCBs affect ionic migration, and
presents in this report a summary of the results of his investigation. |
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9 (00.4.1)
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The affects of adsorbed water on printed circuit boards, and the process of ionic migration |
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Abstract
This report considers the insulation resistance characteristics of printed circuit
boards (PCBs) and the effects of ionic migration in environmental testing. By
measuring insulation resistance in a variety of environmental test conditions, the
authors have determined that the initial changes in insulation resistance values is
caused by water adsorption*1 and electrolysis. While investigating the occurrence of
ionic migration, the authors were able to confirm that metal ions eluted in response to
changes in the pH near the electrodes. These changes in pH were determined to have
been caused by the electrolysis of water, which affected both pH and applied voltage.
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4 (97.10.1) |
Evaluation Mehtod for Ion Migration Using Dew Cycle Test(Part3) |
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Abstract
For our report this time,
we have designed prototype experimenting equipment enabling us to directly observe
dew condensation conditions, thus allowing us to investigate the causes of Dendrites
growing in the Dew Condensation Cycle Test. We have performed experiments to confirm
changes in dew condensation conditions and also to confirm the relationship between
dew condensation and the growth of Dendrites. At this time, we would like to report on
the results of repeated test cycles confirming that water from dew condensation covering
the gap between electrodes causes the substrate surface to become subject to wetting
and causes Dendrites to grow. |
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2 (96.11.1)
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A Consideration of Methods for Evaluating Reliability of Electronic Parts-Concerning
Methods of Continuously Evaluating Ion Migration- |
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Abstract
Many kinds of testing methods are being explored for use in evaluating
reliability. This report examines methods of evaluating reliability of
electronic parts and finding the causes of performance degradation and
malfunction for which intermittent testing isn't effective. Evaluation is made by
continuously measuring insulation resistance of printed circuit boards (PCB) while
applying environmental stress, thus monitoring characteristic values throughout the
time these values are fluctuating. |
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1 (96.4.1) |
Evaluation Mehtod for Ion Migration Using Dew Cycle Test(Part1) |
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Abstract
In this
paper, we shall present a technical examination of the dew cycle test chamber and actual
examples of the evaluation process. We shall also report our findings on the effectiveness
of the test chamber.
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1 (96.4.1) |
Evaluation Mehtod for Ion Migration Using Dew Cycle Test(Part2) |
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Abstract
In this report (Part 2), we shall discuss how the test
chamber has made possible abruptly raising the temperature from a normal temperature
range (hereafter called low temperature) to a higher range of temperature and humidity
(hereafter called high temperature). The test chamber has also made possible greater
fidelity in reproducing the market environment in tests.
In addition, we have confirmed the relationship between the speed at which ion
migration forms and the quantity of dew condensation forming in the test chamber when
temperature and humidity conditions are changed.
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