E. Engelien

Technische Universit├Ąt Dresden, Dresden, Saxony, Germany

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Publications (4)0 Total impact

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    ABSTRACT: For electronic medical devices which are intended to function inside the human body is very important to keep unchangeable their structural and functional properties under an influence of aggressive physiological factors. For stability testing of some electronic materials in laboratory conditions a simulation of human body fluid environment has been used. Sn-contained electronic packaging materials as a) FR4 + 1.2 44 m chemical Sn; b) FR4 + hot air leveling (HAL) Sn and c) FR4 + Sn 3.5 Ag 0.7 Cu were brought in dynamical interaction with artificial blood plasma, cerebrospinal fluid and 0.9% NaCl solution. Alterations in the surface topography and its chemical composition were studied. Materials mass losses in the surface ratio were determined depending on the soaking time. As a protection procedure against the influence of aggressive fluidic environment 1 mum and 2.5 mum layers of parylene C were deposited on chemical Sn and HAL Sn surfaces. Hydrolytic stability of protected materials has been determined.
    Electronics Technology, 2008. ISSE '08. 31st International Spring Seminar on; 06/2008
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    ABSTRACT: Investigation methods on polymer encapsulation were implemented to determine the quality of a polymer coating on electronic devices against migration and diffusion. Therefore the major goal was to evaluate a membrane of Parylene C clamped in a frame. Two different fluids in chambers on each side of the membrane, bi-distillated water and water with solute salt, generate concentration gradient. The potential drop drives ions through the membrane. With the analysis of the conductivity in the chamber with bi-distilled water the transmission rate of the molecules can be determined in dependence of mass and thickness to area and time. These tests have shown a coefficient for the transmission rate of NaCl. The inspection with the scanning electron microscope as well as measuring the surface roughness conducted to first information about thin Parylene C layers.
    Electronics Technology, 2008. ISSE '08. 31st International Spring Seminar on; 06/2008
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    ABSTRACT: Thick film electronic packaging materials based on Ag-Pt (C4729), Ag-Pd (C2030) and Pt (LPA 88-11) conductive pastes were tested on their properties under the influence of flowing artificial blood plasma (ABP), artificial cerebrospinal fluid (ACF) and physiological solution (0.9% NaCl) for the evaluation of their biostability grade in vitro. The degradation effects were studied by means of microscopic investigations, measurements of a surface free energy, determination of mass losses and analysis of a chemical content. Materials were stressed in fluid mediums during the periods of up to 60 days at the temperature of 60degC, pH value of (8-10) and flow velocity of 0.15 m/s in systems with a directional flow and by an unidirectional fluid circulation. Based on SEM-EDX analysis, formation of silver sulphide (Ag2S) in form of yellow-brown precipitate has been observed on Ag-Pt surfaces, which were influenced by ABP and ACF; a partly dissolution of Zn and Na particles from pastes glass matrix was supposed. No significant alterations in chemical content were revealed in case of interactions between Ag-Pt thick films and 0.9% NaCl. Ag-Pd surfaces were more stable due to formation of the protection palladium oxide (PdO) film. A very good stability have shown Pt-layers.
    01/2008;
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    ABSTRACT: In electronics, and especially in medicine technology, the significance of polymers rises at the present time. According to various publications about properties of polymers from different manufacturers, polymers have good dielectric properties, high conformity of coating, low permeability and high stability. Consequently, polymers are a good choice for many different applications. They allow flexible passivation for protection against harmful substances from dust to molecules in liquids. In this context the determination of the diffusion coefficient allows important insight into the protection performance of different polymers. At the example of a 1% NaCl-solution the permeability of different housing materials was measured as a parameter of their protection performance. These tests were broadened by experiments of the optic and geometric surface properties and the determination of the materialspsila adhesion forces. As housing polymers of electronic devices were examined a non-elastic and a flexible solder resist, a sealing wax, a sole gel as well as a Chlor-Poly-Para-Xylylen.
    01/2008;