Juha Karppinen
Aalto University
20 Papers
115 Citations
Juha Karppinen is an academic researcher from Aalto University. The author has contributed to research in topics: Temperature cycling & Power cycling. The author has an hindex of 9, co-authored 20 publications. Previous affiliations of Juha Karppinen include Helsinki University of Technology.
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Papers
Cycle aging of commercial NMC/graphite pouch cells at different temperatures
TL;DR: In this paper, a commercial 40-A-h pouch-type lithium-ion cells with NMC/graphite chemistry was studied at different cycling temperatures (room temperature, +45°C, and +45ÂC charge +65ÂC discharge) and the aging mechanisms were characterized by electrochemical impedance spectroscopy and post-mortem analysis.
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Evolution of microstructure and failure mechanism of lead-free solder interconnections in power cycling and thermal shock tests
Tomi Laurila,Toni T. Mattila,Vesa Vuorinen,Juha Karppinen,Jue Li,Mika Sippola,Jorma Kivilahti +6 more
TL;DR: Failure mechanisms of lead-free solder interconnections in power cycling and thermal shock tests have been investigated and it is found that the failures in both cases were induced by recrystallization-assisted crack nucleation and propagation.
79
Reliability of Lead-Free Solder Interconnections in Thermal and Power Cycling Tests
TL;DR: In this paper, a 3D board-level finite-element analysis with local models was carried out to estimate the reliability of the solder interconnections under various test conditions, including thermal shock test, local thermal cycling test (resistors embedded in the board around the package), and heat generation in the die.
51
Shock impact reliability characterization of a handheld product in accelerated tests and use environment
TL;DR: The drop test results showed that, even though the test board design and supporting method have a marked influence on the strain conditions and lifetime of solder interconnections, the primary failure mode and mechanism under the product-level drop tests is comparable to that typically encountered in the standard JEDEC JESD22-B111 board- level drop tests.
27
Thermal simulation of high-power Li-ion battery with LiMn1/3Ni1/3Co1/3O2 cathode on cell and module levels
TL;DR: In this article, the authors presented a thermal modeling of temperature rise in high-power Li-ion battery cells and modules and validated the simulation results by experiments and showed that entropy heat generation plays a significant role in heat generation of Li-ION battery cells.
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