On the electrochemical migration of copper in electronics – effects of frequency
Korpinen, Katriina (2025-11-14)
Väitöskirja
14.11.2025
Lappeenranta-Lahti University of Technology LUT
Acta Universitatis Lappeenrantaensis
School of Energy Systems
School of Energy Systems, Sähkötekniikka
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Julkaisun pysyvä osoite on
https://urn.fi/URN:ISBN:978-952-412-335-8
https://urn.fi/URN:ISBN:978-952-412-335-8
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Tiivistelmä
In this doctoral dissertation, the electrochemical migration (ECM) of copper in electronics is studied, focusing on the effects of square wave frequency. The primary objective is to determine how different frequencies impact the time to failure (TTF) caused by the ECM of copper. The study is motivated by the increasing density of electronic components in devices and the need for reliable performance in harsh environments. The research questions address the measurement of ECM from an electronics perspective, the impact of square wave signal frequency on ECM, and the potential new phenomena revealed by higher frequencies.
The experimental setup comprises a custom-designed printed circuit board (PCB) with integrated current and temperature sensors, a signal generator and a driver circuit for producing square wave signals, and a data acquisition system for monitoring and logging data. The experiments were conducted using ten square wave frequencies between 5 Hz and 100 kHz using a unipolar 12 V square wave signal. Additional tests were performed using a 6 V square wave and direct current (DC). Video analysis, Weibull analysis, and SEM imaging were methods applied to produce the results.
The results demonstrate a negative correlation between frequency and TTF, indicating that higher frequencies accelerate ECM or that at higher frequencies the dendrites have a higher current-carrying capacity. The time for the first dendrite to attach to the anode is unaffected by frequency, but once the first dendrite has attached, the current increases more rapidly at higher frequencies. The study also revealed that the total voltage exposure may have a more significant impact on the ECM than the root mean square (RMS) voltage. Scanning electron microscope (SEM) imaging and energy-dispersive X-ray spectroscopy (EDS) analysis conducted in this study showed that the dendrite structures vary due to other factors, with no clear correlation with frequency.
The findings of this doctoral dissertation contribute to the understanding of ECM in electronics and provide insights for designing more reliable electronic devices. Future research could explore the effects of even higher frequencies and different square wave duty cycles on ECM, as well as the impact of environmental factors such as contamination.
The experimental setup comprises a custom-designed printed circuit board (PCB) with integrated current and temperature sensors, a signal generator and a driver circuit for producing square wave signals, and a data acquisition system for monitoring and logging data. The experiments were conducted using ten square wave frequencies between 5 Hz and 100 kHz using a unipolar 12 V square wave signal. Additional tests were performed using a 6 V square wave and direct current (DC). Video analysis, Weibull analysis, and SEM imaging were methods applied to produce the results.
The results demonstrate a negative correlation between frequency and TTF, indicating that higher frequencies accelerate ECM or that at higher frequencies the dendrites have a higher current-carrying capacity. The time for the first dendrite to attach to the anode is unaffected by frequency, but once the first dendrite has attached, the current increases more rapidly at higher frequencies. The study also revealed that the total voltage exposure may have a more significant impact on the ECM than the root mean square (RMS) voltage. Scanning electron microscope (SEM) imaging and energy-dispersive X-ray spectroscopy (EDS) analysis conducted in this study showed that the dendrite structures vary due to other factors, with no clear correlation with frequency.
The findings of this doctoral dissertation contribute to the understanding of ECM in electronics and provide insights for designing more reliable electronic devices. Future research could explore the effects of even higher frequencies and different square wave duty cycles on ECM, as well as the impact of environmental factors such as contamination.
Kokoelmat
- Väitöskirjat [1212]