Electroluminescent devices using a high-temperature stable GaN-based phosphor and thick-film dielectric layer

2002 ◽  
Vol 49 (4) ◽  
pp. 557-563 ◽  
Author(s):  
J. Heikenfeld ◽  
A.J. Steckl
Keyword(s):  
High Temperature ◽  
Thick Film ◽  
Dielectric Layer ◽  
Electroluminescent Devices ◽  
Film Dielectric

scholarly journals High temperature ultrasonic sensor for fission gas characterization in MTR harsh environment

2018 ◽  
Vol 170 ◽  
pp. 04008
Author(s):  
O. Gatsa ◽  
P. Combette ◽  
E. Rozenkrantz ◽  
D. Fourmentel ◽  
C. Destouches ◽  
...  
Keyword(s):  
High Temperature ◽  
Thick Film ◽  
Screen Printing ◽  
Bismuth Titanate ◽  
Elevated Temperatures ◽  
Ultrasonic Sensor ◽  
High Resistivity ◽  
Materials Testing ◽  
Coupling Coefficients ◽  
Film Fabrication

In the contemporary world, the measurements in hostile environment is one of the predominant necessity for automotive, aerospace, metallurgy and nuclear plant. The measurement of different parameters in experimental reactors is an important point in nuclear power strategy. In the near past, IES (Institut d’Électronique et des Systèmes) on collaboration with CEA (Commissariat à l’Energie Atomique et aux Energies Alternatives) have developed the first ultrasonic sensor for the application of gas quantity determination that has been tested in a Materials Testing Reactor (MTR). Modern requirements state to labor with the materials that possess stability on its parameters around 350°C in operation temperature. Previous work on PZT components elaboration by screen printing method established the new basis in thick film fabrication and characterization in our laboratory. Our trials on Bismuth Titanate ceramics showed the difficulties related to high electrical conductivity of fabricated samples that postponed further research on this material. Among piezoceramics, the requirements on finding an alternative solution on ceramics that might be easily polarized and fabricated by screen printing approach were resolved by the fabrication of thick film from Sodium Bismuth Titanate (NBT) piezoelectric powder. This material exhibits high Curie temperature, relatively good piezoelectric and coupling coefficients, and it stands to be a good solution for the anticipated application. In this paper, we present NBT thick film fabrication by screen printing, characterization of piezoelectric, dielectric properties and material parameters studies in dependence of temperature. Relatively high resistivity in the range of 1.1013 Ohm.cm for fabricated thick film is explained by Aurivillius structure in which a-and b-layers form perovskite structure between oxides of c-layer. Main results of this study are presented and discussed in terms of feasibility for an application to a new sensor device operating at high temperature level (400°). Piezoelectric parameters enhancement and loss reduction at elevated temperatures are envisaged to be optimized. Further sensor development and test in MTR are expected to be realized in the near future.

Reliability of Au-Ti for High Temperature Termination on Ferrite LTCC Inductors

2013 ◽  
Vol 2013 (HITEN) ◽  
pp. 000039-000045 ◽  
Author(s):  
James Galipeau ◽  
Matt Gerlach
Keyword(s):  
High Temperature ◽  
Thermal Shock ◽  
Thick Film ◽  
Thermal Ageing ◽  
Wire Bonding ◽  
Sputter Deposited ◽  
Commercial Applications ◽  
The Stability ◽  
Terminal Structure ◽  
Pull Tests

While ferrite Low Temperature Co-fired Ceramic (LTCC) inductor and transformer developments have undergone thermal shock and high temperature aging that focused on the stability of their electrical characteristics (resistance, inductance), little attention has been paid to their termination reliability at high temperatures. Testing has been done on AgPt and AgPd terminations with Ag5Cd95 and Pb88Sn10Ag2 solders for 2000 and 25 hrs, respectively. However, Ag5Cd95 is unusable in commercial applications due to ROHS restrictions while Pb88Sn10Ag2 is undesirable because of the high lead content. Sn96 solder and wire bonding are common attachment methods that have not been vetted. Initial investigations show that high Sn solders may interfere with bonding between the AgPt and AgPd termination materials and the ferrite bulk of the part. An alternative terminal structure for using Sn96 solder is created by electroplating Au and Ni; however, electroplating to ferrite is challenging due to the masking involved. Also, the preferred materials for wire bonding are thick film, thin film or electroplated Au. To this end an alternative termination structure using Au sputter deposited onto sputter deposited Ti is being investigated. This structure was chosen for its potential to be a lower cost alternative to thick film Au and for its potential for simpler manufacturing than electroplating. Tests involved measuring bond strength and resistance after thermal ageing and thermal shock. Baseline solder joint pull tests show strength comparable to other termination methods. Some issues with solder wetting of the terminals have been noted.

Mobile Packaging and Interconnect Trends

2014 ◽  
Vol 2014 (DPC) ◽  
pp. 1-21
Author(s):  
Brandon Prior
Keyword(s):  
Shear Strength ◽  
High Temperature ◽  
Thick Film ◽  
Cross Sections ◽  
Shear Test ◽  
Short Review ◽  
Test Machine ◽  
Die Attach ◽  
Shear Failures ◽  
Film Substrate

This paper will focus on emerging and fast growth package solutions to meet mobile products' density and cost requirements. A short review of where package miniaturization and modularization has taken us so far, and where it will lead in the next 5 years. Teardowns of high density systems and packages will be used to illustrate key points. Low temperature Ag sintering technology provides a lead-free die attachment compatible with high temperature (300°C) applications. Previous work with Ag sintering has required some pressure during the sintering process or been limited to small area die. In this paper, a pressureless sintering of micro-scale silver paste procedure is presented for large (8mm x 8mm) area die. Experimental combinations included: Ag metallized Si die, Au metallized Si die, Ag thick film substrate metallization, Au thick film substrate metallization, PdAg thick film metallization and sintering temperature. For Au metallization (die and/or substrate), the initial shear strength results were good with 8mm x 8mm die sintered at lower temperatures (200°C). The shear strength was out range of our shear test machine (100 kg), corresponding to >15.3 MPa. However, after aging for 24 hours at 300°C, the shear strength dropped significantly to 40.38 Kg (6.183 MPa). An SEM was used to characterize cross sections of as-built and aged sample. The decrease in die shear strength with high temperature sintering (250°C and 300°C) or high temperature aging is attributed to surface diffusion of Ag along the Au surface resulting in a dense Ag layer adjacent to the Au surface and a depletion layer within the die attach on the opposite side of the the dense Ag layer. Shear failures occurred through the depleted region. For Ag metallization, no decrease in shear strength was observed with 300°C aging. Shear strength of 8x8cm2 dies was out range of our shear test machine (>100 kg, >15.3 MPa) as-built. The shear strength remained out of range (>15.3MPa) after more than 2000 hours of 300C aging.

HIGH TEMPERATURE PROPERTIES OF MINIATURIZED THICK-FILM COMPONENTS

2012 ◽  
Vol 2012 (CICMT) ◽  
pp. 000400-000405
Author(s):  
Damian Nowak ◽  
Andrzej Dziedzic ◽  
Tomasz Piasecki ◽  
Tomasz Baraniecki ◽  
Jacek Reiner
Keyword(s):  
High Temperature ◽  
Laser Beam ◽  
Thick Film ◽  
Nd:Yag Laser ◽  
Laser Cutting ◽  
Laser System ◽  
Frequency Range ◽  
High Temperature Properties ◽  
Conductive Path ◽  
Conductive Films

This paper presents systematic studies of thick-film or LTCC microcomponents (capacitors, inductors) made with the aid of laser-shaping and operating at temperature up to 450 °C. The minimum dimensions i.e. conductive path width and spacings were about 30 μm. Such small patterns have been created by laser cutting of fired Au- or Ag-based conductive films. Laser system equipped with Nd:YAG-laser (beam wavelength of 1064 nm) was applied. The inductance, capacitance, as well as parasitic impedances were measured in the frequency range from 10 kHz to 110 MHz and temperature between 25 °C and 450 °C.

Chemical selective coating of nickel / palladium / gold metallization on screen-printed thick film on LTCC and Al2O3 ceramic for high temperature applications

2012 ◽  
Vol 2012 (CICMT) ◽  
pp. 000334-000338
Author(s):  
Jens Müller ◽  
Thomas Mache ◽  
Torsten Thelemann
Keyword(s):  
High Temperature ◽  
Thick Film ◽  
Low Cost ◽  
Gold Wire ◽  
Wire Bonding ◽  
Pure Gold ◽  
Al2o3 Ceramic ◽  
Selective Coating ◽  
Silver Palladium ◽  
Silver Silver

Electroless plating on silver is a low cost alternative to printing of mixed metals or pure gold paste systems on LTCC. It overcomes the necessity to have material transitions from inner to outer layers or from conductor lines to wire bonding- or solder-pads. Since no commercial process and material set for silver thick film conductors has been available on the market a proprietary Ni/Pd/Au coating technology was developed for the use on silver inks for LTCC and Al2O3-ceramic as a base for both soldering and wire bonding. The work included the screening of different chemicals as well as several silver paste systems from two commercial vendors. Conductor adhesion, plating layer thicknesses, plating accuracy, (lead free) solderability and gold wire-bondability were assessed to optimize the process. Layers of about 5 microns Ni, (0.1 to 0.3) microns Pd and (0.05 to 0.15) microns Au were electrolessly deposited. The developed Ni-Pd-Au finish is an economical alternative with only about a quarter of the cost compared to the conventional use of silver, silver / palladium and gold compounds for ceramic substrates. This technology allows coating of the structures down to a fine pad size of 200×200 microns and a minimum line width of 100 microns, without reducing the adhesion mechanism between thick-film metallization and ceramic substrate. By covering of pure conductors with high temperature glass or dielectrics, further material saving is possible. Besides, the process offers also very good coating of structures in cavities.

Evaluation of screen-printable type S (Pt-PtRh) thermocouples on different ceramic substrates

2016 ◽  
Vol 2016 (CICMT) ◽  
pp. 000053-000057
Author(s):  
Jaroslaw Kita ◽  
Sven Wiegärtner ◽  
Alistair Prince ◽  
Peter Weigand ◽  
Ralf Moos
Keyword(s):  
High Temperature ◽  
Thick Film ◽  
Screen Printing ◽  
Temperature Sensors ◽  
Electrical Characteristics ◽  
Buried Structures ◽  
Ceramic Substrates ◽  
Temperature Characteristics ◽  
Film Type ◽  
Thick Film Technology

Abstract The application of thermocouples as temperature sensors has been well known and has already been established for many years. However, for classical thick-film technology using screen-printing and firing, no standardized solutions exist. The here-presented newly developed PtRh thick-film compositions (90% Pt,10% Rh) allows to construct thick-film type S thermocouples (Pt/PtRh), following the IEC temperature characteristics. They can be fired in air, and therefore can be easily integrated into existing thick-film components and devices. In an earlier study, the new Pt-Rh composition was successfully tested on alumina substrates. Their electrical characteristics is equal with classical wire type S thermocouples. This study continues the investigations of thick-film thermocouples. We tested the newly developed pastes for high temperature applications on alumina substrates and evaluated the application of the new screen-printable type S thermocouples on LTCC ceramics. Three possible configurations were investigated: deposited on already fired LTCC substrates (post-fired), screen-printed and co-fired with LTCC tapes on the top surface as well as as buried structures. The paper presents the results of our evaluation and discusses further possible applications.

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