Complementary EIS/FTIR study of the degradation of adhesives in electronic packaging

Adhesives are widely used in electronic packaging and of vital importance of the reliability of electronic systems. A deep understanding of the degradation mechanism of adhesives under corrosion load plays a key role in life time prediction. Unfortunately, most of the common reliability test are destructive. The present approach combine the non-destructive methods Electrochemical Impedance Spectroscopy (EIS) and the Fourier Transformed Infrared Spectroscopy (FTIR) as a powerful tool in complementary manner to describe the degradation mechanism and kinetics of two epoxy based adhesives, which are commonly used in electronic packaging. It is demonstrated that the application quality is the dominating impact on the optimization of the life time

Anodizing - interplay between bath aging and oxide formation and properties

The present study investigates the interplay between ongoing bath aging during the anodizing process and the formation and properties of the anodic formed oxide layers on AA 1050 in sulfuric acid. The change in the bath over the time of use is studied by controlling the conductivity of the bath. The pH value and the concentration of Al3+ ions in the bath are simultaneously measured. The kinetic of the oxide formation depending on the bath aging is electrochemically investigated by repetitive potential controlled anodizing of reference samples. Supplementary material diagnostics by SEM and infrared reflection–absorption spectroscopy show a significant decrease of the oxide film thickness as well as the molecular composition with ongoing bath aging

An FT-IRRAS-study of anodic oxide films on aluminum alloys and the impact of bath aging

This present work studies the influence of the anodizing bath aging on the oxide formation and the oxide layer structure. The ongoing bath aging was mainly monitored by measurements of the electrolyte conductivity and concentration of Al3+ concentration in the electrolyte. SEM measurement clearly shows the changing of the oxide thickness as well as the porosity with ongoing bath aging. The molecular structure of the oxide film studied by FT-IRRAS shows that SO42- and PO43- are incorporated in the oxide layers. With ongoing bath aging the part of incorporated amount of sulfate decreases, whereas the amount of phosphates increases as confirmed by EDX analysis. No significant incorporation of copper or copper oxides were detected inside the anodic oxide layer

A Flexible Micro-Electrode Array with an Embedded Flexible CMOS-Chip for Medical Applications

Micro-electrodes and micro-electrode arrays are essential in a variety of medical applications like deep brain stimulators, cochlear implants or retinal implants. To have a close interface to the human tissue for stimulating neurons or recording action potentials, these micro-electrode arrays must be flexible and should have a large area and a large number of electrodes. In order to electrically connect such large electrode numbers in implantable devices with integrated electronics, simple wiring is no longer possible. In fact to reduce the number of conductor paths, electrodes have to be connected via a bus system. Therefore it is necessary to bring CMOS circuitry in close proximity to the stimulation electrodes, by this forming an "intelligent electrode". To keep the system flexible th e silicon chips have to be thinned. In this paper the design and fabrication steps of such a flexible intelligent implantable MEAsystem and results on mechanical and electrical properties are presented. Furthermore, alternatively coating of the electrodes with carbon nanotubes by electrophoresis has been investigated and will be presented

Heteromeric AtKC1·AKT1 Channels in Arabidopsis Roots Facilitate Growth under K+-limiting Conditions*

Plant growth and development is driven by osmotic processes. Potassium represents the major osmotically active cation in plants cells. The uptake of this inorganic osmolyte from the soil in Arabidopsis involves a root K+ uptake module consisting of the two K+ channel α-subunits, AKT1 and AtKC1. AKT1-mediated potassium absorption from K+-depleted soil was shown to depend on the calcium-sensing proteins CBL1/9 and their interacting kinase CIPK23. Here we show that upon activation by the CBL·CIPK complex in low external potassium homomeric AKT1 channels open at voltages positive of EK, a condition resulting in cellular K+ leakage. Although at submillimolar external potassium an intrinsic K+ sensor reduces AKT1 channel cord conductance, loss of cytosolic potassium is not completely abolished under these conditions. Depending on channel activity and the actual potassium gradients, this channel-mediated K+ loss results in impaired plant growth in the atkc1 mutant. Incorporation of the AtKC1 subunit into the channel complex, however, modulates the properties of the K+ uptake module to prevent K+ loss. Upon assembly of AKT1 and AtKC1, the activation threshold of the root inward rectifier voltage gate is shifted negative by approximately −70 mV. Additionally, the channel conductance gains a hypersensitive K+ dependence. Together, these two processes appear to represent a safety strategy preventing K+ loss through the uptake channels under physiological conditions. Similar growth retardation phenotypes of akt1 and atkc1 loss-of-function mutants in response to limiting K+ supply further support such functional interdependence of AKT1 and AtKC1. Taken together, these findings suggest an essential role of AtKC1-like subunits for root K+ uptake and K+ homeostasis when plants experience conditions of K+ limitation