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Electronics Technology (ISSE), 2012 35th International Spring Seminar on

Date 9-13 May 2012

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Displaying Results 1 - 25 of 101
  • Electrical conductivity of inkjet printed silver tracks

    Publication Year: 2012 , Page(s): 1 - 4
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (519 KB) |  | HTML iconHTML  

    The work aims to assess the conductivity of Silver tracks printed using a state-of-the-art PixDro LP50 inkjet printer which has the capability to print conductive tracks with width as low as 50μm. The conductivity of tracks with different dimensions is measured using a Keithley measurement setup. The equivalent resistivity depends on the material, printing technology and geometrical dimensions. Profile measurements indicate a track thickness of around 300nm. The optimal printing resolution appears to be 450dpi, ensuring conductivity for all selected track widths from 50μm to 400μm. This paper analyses the influence of the layout on the electrical properties with a focus on determining the minimum metal quantity necessary to have tracks with good conductivity. View full abstract»

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  • Influence of the organic transistors' layout on electrical parameters

    Publication Year: 2012 , Page(s): 5 - 8
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (598 KB) |  | HTML iconHTML  

    The paper aims to assess how the geometry of the organic thin film transistors (OTFTs) influences their electrical parameters. The transistors have polytriarylamine (PTAA) as semiconductor. Several geometries will be investigated for transistors fabricated in a single batch. These geometries include simple electrodes, inter-digitated electrodes and circular electrodes. The electrical parameters considered are threshold voltage, mobility, ON-OFF ratio, the sub-threshold swing and the contact resistance. All the measurements are performed with a calibrated semiconductor analyzer in accordance to the IEEE 1620 standard. The paper discusses the trade-off between the ease of fabrication and the increase in performance of these devices. View full abstract»

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  • Heat protection coatings for high temperature electronics

    Publication Year: 2012 , Page(s): 9 - 14
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (476 KB) |  | HTML iconHTML  

    Highly-integrated electronic devices and printed circuit boards need to be protected against overheating. In this disquisition a concept is introduced to improve the thermal management of coated assemblies by means of functional additives based on earlier works [4]. It has already been proven that paraffin wax, zeolite molecular sieve and silica gel have the potential as thermal energy storage systems due to phase transition effects and sorption [1], [5], [6]. Here the cooling effects of these materials were analyzed by using a heating element (constantan on ceramic substrate) and chip resistors with different package sizes (2512, 1206, 0805, 0603). The covering of these testing elements with the investigated additives lead to a significant delayed heating and therewith to a short-period heat protection at pulse load condition. Nevertheless a re-cooling of the system could regenerate the cooling effects of the additives for multiple utilization; paraffin wax due to refreezing and zeolite/silica gel due to rehydration. The Application for coating technology indicates a significant improvement of thermal properties. View full abstract»

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  • Influence of curing technologies on the application quality of PTF-conductive pastes

    Publication Year: 2012 , Page(s): 15 - 18
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (373 KB) |  | HTML iconHTML  

    The Polymer Thick Film Technology permits a cost efficient production of electronic circuits. The technology permits through a screen printing process the application of different polymer pastes of flexible and rigid substrate. This allows the production of electronic circuits in a short time. After that are develop the functional characteristics of the polymer pastes through a temperature process. Like any technology have this some disadvantages such as low electrical conductivity and limited assembly capability. View full abstract»

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  • Organic based sensors: Novel screen printing technique for sensing layers deposition

    Publication Year: 2012 , Page(s): 19 - 24
    Cited by:  Papers (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (964 KB) |  | HTML iconHTML  

    This paper presents a research focused on development of low-cost manufacturing process which enables fabrication of accurate organic humidity sensors, where only screen printing is used for all layers deposition. It means that not only the interdigital structures with 50 μm line and space, but also phatolocynine sensing film and protective polymer layer are screen printed. The interdigital structures are printed by advanced screen printing in order to replace complex an expensive vacuum processes. In the frame of this research a novel screen printing technique for deposition of low viscose organic sensing film was also developed, where non-standard precise stainless steel Beta mesh was used for screens. View full abstract»

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  • Current transport mechanisms of amorphous n-doped silicon carbide/crystalline silicon heterostructure: Impact of nitrogen dopation

    Publication Year: 2012 , Page(s): 25 - 30
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (419 KB) |  | HTML iconHTML  

    Amorphous silicon carbide (a-SiC) thin films were prepared by PECVD deposition technique. A gas mixture of SiH4, CH4 and NH3 was directly introduced into the reaction chamber through a shower head. Properties of deposited films were studied by electrical measurement. Temperature dependences of forward (FW) current-voltage (I-V) characteristics of Al/a-SiC/c-Si(p)/Al structures are shown and analyzed in this paper. Parameters as saturation current and activation energies were measured and calculated from forward biased I-V curves. Identification of bonds at surface of amorphous layers by FTIR was presented. View full abstract»

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  • Energetic analysis of solder paste deposits as reference for soldering with selective heat

    Publication Year: 2012 , Page(s): 31 - 36
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (524 KB) |  | HTML iconHTML  

    Strictly speaking standard reflow soldering processes are inefficient in terms of energy consumption. A large amount of energy is needed to heat up comparatively small solder joints. As a result the whole electronic assembly is stressed with heat, of which only a fraction is going into soldering. A reduction of process temperatures would improve this disproportion. To compensate for the resulting lack of energy, an exothermic reaction, releasing additional heat inside the solder paste deposits, could be applied. The potential of such a process has already been proven in earlier works [1], [5]. For the adjustment of such a sensitive process a better understanding of the energetic requirements for solder paste deposits in dependence of their size and temperature is required. In this work such results are generated by a practical measuring approach. Here, a chip resistor is used as a model to melt up particular solder joints through joule heating. The thermal energy is calculated by measuring electrical power over time. View full abstract»

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  • Cross-sensitivity of humidity sensor layers based on organic materials

    Publication Year: 2012 , Page(s): 37 - 40
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (654 KB) |  | HTML iconHTML  

    This article deals with the research of an impact of various gases and vapours on electrical parameters of phthalocyanine. Cross-sensitivity was researched in order to exclude a negative impact of organic vapours on humidity sensor. Thin layer of phthalocyanine was exposed to various vapours, and then responses of its electrical characteristics were measured. This suitable material for humidity sensors, was deposited from the liquid phase on a substrate with interdigital electrodes and than exposed to the effect of analytes. Subsequently, the impedance characteristic of this thin film layer was measured. The comparison of responses to various gases and vapours is discussed in more detail as well. View full abstract»

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  • Influence factors of warpage reduction of thin dies by capillary action

    Publication Year: 2012 , Page(s): 41 - 46
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (372 KB) |  | HTML iconHTML  

    This paper examines a new technology to overcome the warpage of thin dies during electronics assembly. A liquid is encased in the gap between substrate and die, which acts as capillary. Consequently the die is planarized due to capillary pressure caused by the capillary action in the gap. Influencing factors on this effect, like gap height, level and orientation of die warpage, volume of liquid and the kind of the used liquid, were investigated. It was found that the success of the planarization depends strongly on the warpage orientation of the die. In case of a concave warpage orientation the technology is sensitive on the volume of the liquid, the gap height and of the warpage level in the initial state. In contrast, the planarization works significantly better for a convex warpage orientation and is less sensitive to parameter changes. The reasons for these differences were explained by a mechanical beam model. View full abstract»

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  • Design of a singlet oxygen generator based on LED emitters

    Publication Year: 2012 , Page(s): 47 - 49
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (261 KB) |  | HTML iconHTML  

    This article deals with the research of singlet oxygen generation using phthalocyanine photosensitizer. Singlet oxygen is extraordinary reactive and can be used in many applications such as photodynamic therapy, disinfection or chemical synthesis. For singlet oxygen generation, the photosensitized method in a new developed generator based on LED emitters was used. The amount of singlet oxygen generated by LED emitters was compared with laser excitation. The principle of measurement, design of a singlet oxygen generator and control unit are discussed in more detail. View full abstract»

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  • Possibilities of making 3D resistors in LTCC technology

    Publication Year: 2012 , Page(s): 50 - 54
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (401 KB) |  | HTML iconHTML  

    The Article deals with three-dimensional (3D) resistors making in Low Temperature Co-fired Ceramic (LTCC) substrates. It is especially focused on a manner of fabrication and design for reliability and reproducibility. 3D resistors are created of vias filled with a resistive paste. To fill the vias, stencil-printing is used. There are two ways of their arrangement through more layers - directly in line or zigzag. The research targets on finding the optimal count of connected layers, structure of resistive paste after firing, scattering of values of resistivity. View full abstract»

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  • Pressure sensing: A novel method for characterizing the processing zone in Vapour Phase Soldering systems

    Publication Year: 2012 , Page(s): 55 - 58
    Cited by:  Papers (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (587 KB) |  | HTML iconHTML  

    Vapour Phase Soldering (VPS) [1] has become a significant alternative method for reflow soldering in the last years [2-3]. Since the technology is based on heat transfer principles, which are totally different from the conventional reflow technologies (forced convection or IR), a new approach is needed for the characterization of the processing zone inside the vapour chamber. This paper presents the results of a novel method for characterization: the measurement of pressure differences in the processing zone of a VPS tank. For this purpose, high resolution pressure sensors were applied to a batch type, experimental VPS station. High resolution of the measurement range is a key factor of the method due to the small pressure differences of the process. The measurements correlate to the Galden vapour density and the temperature, which are also important aspects of the experiment. View full abstract»

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  • Investigations on current capabilities of PEDOT:PSS conductors

    Publication Year: 2012 , Page(s): 59 - 64
    Cited by:  Papers (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (426 KB) |  | HTML iconHTML  

    The organic electronics products becomes every day more and more present, especially known being organic light emitting diodes (OLED), organic photovoltaic cells (OPV) or organic thin film transistors (OFET). It is very important to have a reliable solution for interconnection of these devices in a manner similar to printed circuit boards. This paper will present results on electrical and thermal tests of organic conductors based on poly(3,4-ethylenedioxythiophene) doped with polystyrenesulfonic acid (PEDOT:PSS) that can be used for data and power tracks. The samples are, and will be prepared by screen printing and ink-jetting, having silver paste and respectively ink based terminations. The results have shown that the current capabilities of PEDOT:PSS organic conductive tracks are limited by the dissipated power, due to relatively large resistance. As expected, the screen printed tracks having a higher thickness will have lower resistance. The temperature coefficient (TCR) has been found negative around -1000 ppm/°C. View full abstract»

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  • Complex permeability dependence of commercial LTCC ferritic tape on ambient temperature

    Publication Year: 2012 , Page(s): 65 - 69
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1052 KB) |  | HTML iconHTML  

    This paper deals with material characterization of ferrite LTCC (Low Temperature Co-fired Ceramic) and influence of ambient temperature variation to its complex permeability value. Results of the material characterization (chemical analysis, surface roughness) of commercially available ESL 40011 ferrite tape are presented for the first time. In addition, complex permeability dependence on frequency is determined using previously verified measurement method and developed dispersion model. Complex permeability dependence on ambient temperature variation is also measured in the frequency range up to 1 GHz. Presented results show decrease of complex permeability maximum value with temperature increase from 20°C to 120°C. Cut-back of the useful frequency range of the material is also noticeable in the same temperature range. View full abstract»

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  • Current thermoelectric materials and an evaluation of thermoelectric materials contacting approaches

    Publication Year: 2012 , Page(s): 70 - 75
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (840 KB) |  | HTML iconHTML  

    In this paper a brief selection of state-of-the-art thermoelectric materials is described which are used for thermoelectric power generation. A summary of current advances in the field of thermoelectric (TE) materials which are used for TE power generation is presented. Among them, the class of filled skutterudite is very promising and extensively investigated. Skutterudites offer good power conversion efficiencies, with the high temperature side of the generators reaching up to 600 °C. Higher temperatures result in technological challenges related to thermomechanically induced stress. Additional difficulties at high temperatures can arise with respect to the reliability of the electrical contacts between the TE materials and metal connectors. Some contacting metals (e.g. silver) tend to diffuse into the active thermoelectric legs and thus are unsuitable for various high-temperature TE materials. As a first step towards a cascaded TE heat engine two Bi2Te3 based TE generators have been evaluated with respect to the influence of TE-leg contacting approaches by measuring their figure-of-merit. While the elements of one TE generator were attached by means of vapor phase bonding using a tin based solder, the elements of the second generator were attached with a silver filled epoxy adhesive. View full abstract»

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  • Investigation of thermal properties of power LED illumination assemblies

    Publication Year: 2012 , Page(s): 76 - 83
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (572 KB) |  | HTML iconHTML  

    The reliability and long-term stability of solid-state lighting devices strongly depend on successful thermal management. It is well known that junction temperature instability negatively impacts the lightning properties of LED illuminators. However, for prediction of life time and longterm stability the temperature distribution also inside the color converter must be known. A deeper understanding of these demanding thermal issues is provided in our paper on the base of measurements and simulations also taking into account the spatial power loss distribution due to absorption of light and Stokes shift within the color converter. For this purpose 3-dimensional models were set-up and examined to thermally characterize high-power LED assemblies. Two different types of set-ups were investigated. Moreover, an efficient solution is presented where a junction-to-case thermal resistance below 10 K/W is achieved. View full abstract»

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  • The manufacture process influence on thermal conductivity of polymers thermal interface materials with carbon nanotubes

    Publication Year: 2012 , Page(s): 84 - 88
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (509 KB) |  | HTML iconHTML  

    In this paper the manufacture process influence on thermal conductivity of polymer composites used as the Thermal Interface Material (TIM) is presented. To evaluate the influence of the manufacture factors the design of the experiment technique (DoE) and Analysis Of Variance for the results (ANOVA) were used. From the experiment results one import5ant factor and one important interaction have been specified which have the most important influence on the experiment. The factor is the time of mixing of dispersed carbon nanotubes in the polymer matrix and the interaction is the interdependence between the content of carbon nanotubes in the composite and the way of mixing (piston and mortar or three roller-mill). To evaluate the results the thermal conductivity of the TIMs was taken. View full abstract»

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  • Selective electrochemical etching for the investigation of solder joint microstructures

    Publication Year: 2012 , Page(s): 89 - 94
    Cited by:  Papers (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1126 KB) |  | HTML iconHTML  

    Hereby we introduce a method called selective electrochemical etching for the investigation of solder joint microstructures. The aim of this technique is to remove the tin from the solder joint, which enables the examination of the remaining intermetallic microstructures in such a detail, which is unlike to any other previously established method. In our work we discuss the importance of intermetallic compound (IMC) investigation and compare the existing methods with our proposed technique. Pilot measurement results are also presented on selectively etched SAC (Sn-Ag-Cu) alloy solder joints. We present the found relationship between 1) the soldering methods and parameters, 2) the resulting microstructures, 3) the amount of the removed charge/Sn phase during the etching and 4) shear test results on the different solder joints. In our paper we will also investigate the effect of the etching conditions (e.g. etching time, electrolyte concentration, etc.) in order to reach the optimal etching depth, considering the detail and integrity of the intermetallic structures. View full abstract»

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  • Author's index

    Publication Year: 2012 , Page(s): 388 - 390
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    Freely Available from IEEE
  • Method for in-situ power LEDs' junction temperature measurements

    Publication Year: 2012 , Page(s): 95 - 100
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (285 KB) |  | HTML iconHTML  

    In this work investigations are connected with development of method of LEDs' junctions' temperatures estimation at real operating conditions. Direct junction temperature determination is not possible and alternative methods have to be developed. Suitable, cheap and reliable method for direct estimation of LEDs' junction temperatures during operating of lighting equipment is proposed. It is realized by employing the temperature dependence of LEDs' forward voltage drop. Two different types of LEDs have been investigated at various ambient conditions (air temperatures from 20°C to 45°C) and different current values through LEDs - from 350 mA to 600 mA. Recommendations concerning calibrations, calculations and junctions' temperatures evaluations are presented. Developed method allows achieving of reliable results “in situ” for thermal performance of LEDs using non expensive experimental equipment. View full abstract»

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  • LED lamp - design and thermal management investigations

    Publication Year: 2012 , Page(s): 101 - 106
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (595 KB) |  | HTML iconHTML  

    The aims of this work are connected with development of new method of LEDs' mounting onto the heat sink in lighting equipment. The technique involves usage of copper pins instead of standard MCPCBs. LEDs are soldered on copper pins. Mounting of LEDs demands boring holes in the heat sink and fixing copper pins into the holes by thermal conductive epoxy resin only. LED lamp is made using new technology and LEDs' thermal performance investigations are made at various ambient conditions (air temperatures from 20°C to 45°C) and different current values through LEDs - up to 600 mA. Temperature regimes of operation of power LEDs soldered on MCPCBs and on copper pins (and mounted on heat sink) are experimentally tested and compared. Experimental results show that utilization of copper pins underneath LED thermal pads ensures good dissipation of heat, good manufacturability, enables varied designs of light equipment and is cost effective. View full abstract»

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  • Comparison of two high-end infrared thermography systems with different spectral sensitivity for thermal investigations of sensor heater elements

    Publication Year: 2012 , Page(s): 107 - 113
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (511 KB) |  | HTML iconHTML  

    We discuss the measurement of temperature distributions using thermography, and its limitations due to wavelength and temperature dependent infrared-optical properties of the sample. A typical oxygen sensor has been realized by thick film technology: a platinum heater structure with integrated temperature sensor has been printed on a zirconia substrate. The variation of the temperature of the sensor with the applied heater current has been experimentally investigated by a three-wire resistance measurement and the application of two different high-resolution thermography systems. The first method is an easy and reliable direct method to obtain an average temperature value of the heater structure, whereas thermography gives the spatial distribution of the temperature. Thermography images of the sensor as-built and coated with a high-emissivity varnish are compared. Typical pitfalls in the interpretation of the thermal signature of the device under test resulting from unknown emission coefficients and semitransparency of the substrate material are discussed in detail. View full abstract»

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  • Physical properties of silver inkjet printed circuits

    Publication Year: 2012 , Page(s): 114 - 116
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (311 KB) |  | HTML iconHTML  

    The paper aims to describe methods of dealing with printing issues related to printing metallic nanoparticle inks with micrometric dimensions. The particular focus is on inks containing metal nanoparticles, complexes and metallo-organic compounds that reach acceptable conductivity for the structures. These need to be sintered, the low temperature representing the novel aspect. The work describes the achievement of such electrical tracks with nanoparticle inks printed with commercially available silver ink EMD5603 from Sunchemical. The electrical tracks were printed with different resolutions, on two flexible substrates and the thermal treatment was performed at different temperatures. View full abstract»

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  • Effect of surface treatment on the conductive adhesive interconnection of flexible solar cells

    Publication Year: 2012 , Page(s): 117 - 122
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (631 KB) |  | HTML iconHTML  

    The effects of plasma-treatment on the contact quality of the molybdenum back contact of flexible solar cells interconnected with isotropic conductive adhesives have been studied. The influence of the surface treatment on surface properties like roughness, contact angles and surface energies have been measured and flow characteristics have been analyzed. The contact resistances and microsections have been studied. Pre-treatment might help to increase the spreading of the freshly applied conductive adhesive on a surface, but also enhances the thickness of the polymer layer at the interface. Because the contact geometry largely depends on the dispensing parameter, it was also found that a highly thixotropic adhesive does not show significantly better wetting behavior on the treated surface. The samples without preliminary plasma treatment show better contact resistance in that case. View full abstract»

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  • Packaging of electronic devices for long-term implantation

    Publication Year: 2012 , Page(s): 123 - 127
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    Development of smart medical devices for long-term implantation requires new encapsulation technologies with a special focus on flexible packaging of electronic devices. Biocompatible, high performance polymers seem to be suitable for such applications, however their protective function i.e. suppressing harmful interactions between the human and the foreign body is still unknown. Here, we evaluated this protective function of six polymers with regard to surface properties, water absorption and water solubility. Among all polymers investigated, silicone (low-consistency) showed the best characteristics compared to epoxy resin or polyurethane. View full abstract»

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