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Article
Publication date: 2 April 2019

Roman Koleňák, Igor Kostolný, Jaromír Drápala, Martin Kusý and Matej Pašák

This study aims to solder AlN ceramics with a Cu substrate using an active type Sn-Ag-Ti solder. Soldering was performed with power ultrasound. The Sn3.5Ag2Ti alloy was…

Abstract

Purpose

This study aims to solder AlN ceramics with a Cu substrate using an active type Sn-Ag-Ti solder. Soldering was performed with power ultrasound. The Sn3.5Ag2Ti alloy was first studied.

Design/methodology/approach

It was found to contain a Sn matrix, where both Ag phase – ɛ-Ag3Sn – and Ti phases ɛ-Ti6Sn5 and Ti2Sn3 – were identified. Ti contained in these phases is distributed to the interface with ceramic material. A reaction layer was thus formed. This layer varies in thickness from 0.5 to 3.5 µm and ensures the wettability of an active solder on the surfaces of ceramic materials.

Findings

X-ray diffraction analysis proved the presence of new NTi and AlTi2 phases on the fractured surface. Sn plays the main role in bond formation when soldering the Cu substrate with Sn-Ag-Ti solder. The Cu3Sn and Cu6Sn5 phases, which grow in direction from the phase interface to solder matrix, were found in all cases within the solder/Cu substrate interface. The combination of AlN ceramics/Cu joint maintained a shear strength of 29.5 MPa, whereas the Cu/Cu joint showed a somewhat higher shear strength of 39.5 MPa.

Originality/value

The present study was oriented towards soldering of AlN ceramics with a Cu substrate by the aid of ultrasound, and the fluxless soldering method was applied. Soldering alloy type Sn-Ag-Ti was analysed, and the interactions between the solder and ceramic and/or Cu substrate were studied. The shear strength of fabricated soldered joints was measured.

Details

Soldering & Surface Mount Technology, vol. 31 no. 2
Type: Research Article
ISSN: 0954-0911

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Article
Publication date: 1 February 2003

Dongfeng Zheng, Minbo Tian, Yingqian Wang and Wei He

A silver‐palladium thick film conductor for aluminum nitride (AlN) substrate has been developed. This conductor film on AlN ceramics had low sheet resistivity, high…

Abstract

A silver‐palladium thick film conductor for aluminum nitride (AlN) substrate has been developed. This conductor film on AlN ceramics had low sheet resistivity, high adhesion strength and good wettability with Pb‐Sn solder. The frit powder of lead borosilicate glass was used as inorganic binders to enhance the adhesion between the conductor and ceramics. After sintering the conductor film connected with the AlN substrate through frit bonding, no transition phases but a multilayer structure is present in the interface. The softening point of the glass was important to the adhesion strength of conductor film. In order to achieve good adhesion, it is necessary that the glass has a proper softening point (about 500‐650°C).

Details

Pigment & Resin Technology, vol. 32 no. 1
Type: Research Article
ISSN: 0369-9420

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Article
Publication date: 1 April 2005

Jaroslav Mackerle

Ceramic materials and glasses have become important in modern industry as well as in the consumer environment. Heat resistant ceramics are used in the metal forming…

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Abstract

Purpose

Ceramic materials and glasses have become important in modern industry as well as in the consumer environment. Heat resistant ceramics are used in the metal forming processes or as welding and brazing fixtures, etc. Ceramic materials are frequently used in industries where a wear and chemical resistance are required criteria (seals, liners, grinding wheels, machining tools, etc.). Electrical, magnetic and optical properties of ceramic materials are important in electrical and electronic industries where these materials are used as sensors and actuators, integrated circuits, piezoelectric transducers, ultrasonic devices, microwave devices, magnetic tapes, and in other applications. A significant amount of literature is available on the finite element modelling (FEM) of ceramics and glass. This paper gives a listing of these published papers and is a continuation of the author's bibliography entitled “Finite element modelling of ceramics and glass” and published in Engineering Computations, Vol. 16, 1999, pp. 510‐71 for the period 1977‐1998.

Design/methodology/approach

The form of the paper is a bibliography. Listed references have been retrieved from the author's database, MAKEBASE. Also Compendex has been checked. The period is 1998‐2004.

Findings

Provides a listing of 1,432 references. The following topics are included: ceramics – material and mechanical properties in general, ceramic coatings and joining problems, ceramic composites, piezoceramics, ceramic tools and machining, material processing simulations, fracture mechanics and damage, applications of ceramic/composites in engineering; glass – material and mechanical properties in general, glass fiber composites, material processing simulations, fracture mechanics and damage, and applications of glasses in engineering.

Originality/value

This paper makes it easy for professionals working with the numerical methods with applications to ceramics and glasses to be up‐to‐date in an effective way.

Details

Engineering Computations, vol. 22 no. 3
Type: Research Article
ISSN: 0264-4401

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Article
Publication date: 7 January 2019

Hai Jiang, YiYing Lu, Liwen Ding, Wenzhong Lu, Guifen Fan and Yusheng Shi

Aluminum nitride (AlN) ceramics are suitable substrate and package materials for high-power integrated circuits.

Abstract

Purpose

Aluminum nitride (AlN) ceramics are suitable substrate and package materials for high-power integrated circuits.

Design/methodology/approach

Dense AlN ceramics with Y2O3 and LaF3 as sintering additives are prepared. The effects of these additives on the density, phase composition, microstructure and thermal conductivity of AlN ceramics are investigated.

Findings

Results show that 2 Wt.% Y2O3-doped additive is insufficient for the samples to achieve the full densification sintered at 1,700°C. When LaF3 is added with Y2O3, the samples are perfectly densified at the same sintering condition. The relative density and thermal conductivity of the samples are 97.8-99.07 per cent and 169.104-200.010 W·m-1·K-1, respectively. The density of the samples and their microstructure, especially the content and distribution of secondary phases, is necessary to control the thermal conductivity of AlN ceramics.

Originality/value

Y2O3 and LaF3 additives can effectively promote densification and enhance the thermal conductivity of AlN ceramics in a low sintering temperature, and the AlN ceramics added with Y2O3-LaF3 might have potential applications in package materials for high-power integrated circuits.

Details

Microelectronics International, vol. 36 no. 1
Type: Research Article
ISSN: 1356-5362

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Article
Publication date: 1 January 1989

M. Feil

The similarity of its temperature expansion coefficient to that of silicon, as well as its high thermal conductivity, makes AlN a material suited for application in…

Abstract

The similarity of its temperature expansion coefficient to that of silicon, as well as its high thermal conductivity, makes AlN a material suited for application in microelectronics. A comparison of the various AlN manufacturers shows above all differences in the choice of sintering aids and the type of sintering process. A comparison of a standard paste system (Du Pont) with a new special development (Shoei) demonstrates the need for adapting the pastes to AlN ceramics. Thin film technology is possible at a standard similar to that of Al2O3.

Details

Microelectronics International, vol. 6 no. 1
Type: Research Article
ISSN: 1356-5362

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Article
Publication date: 4 January 2016

M M Rahman, Teodor Grosan and Ioan Pop

The laminar two-dimensional stagnation-point flow and heat transfer of a viscous incompressible nanofluid obliquely impinging on a shrinking surface is formulated as a…

Abstract

Purpose

The laminar two-dimensional stagnation-point flow and heat transfer of a viscous incompressible nanofluid obliquely impinging on a shrinking surface is formulated as a similarity solution of the Navier-Stokes, energy and concentration equations. The model used for the nanofluid incorporates the effects of Brownian motion and thermophoresis. The effect of the dimensionless strain rate, shrinking parameter, Brownian motion parameter and thermophoresis parameter on the flow, temperature and nanoparticle volume fraction is investigated in details. The paper aims to discuss these issues.

Design/methodology/approach

The transformed system of ordinary differential equations was solved using the function bvp4c from Matlab. The relative tolerance was set to 10−10.

Findings

It is found that dimensionless strain rate and shrinking parameter causes a shift in the position of the point of zero skin friction along the stretching sheet. Obliquity of the flow toward the surface increases as the strain rate intensifies. The results indicate that dual solutions exist for the opposing flow case.

Research limitations/implications

The problem is formulated for an incompressible nanofluid with no chemical reactions, dilute mixture, negligible viscous dissipation and negligible radiative heat transfer assuming nanoparticles and base fluid are locally in thermal equilibrium. Beyond the critical point λ c to obtain further solutions, the full basic partial differential equations have to be solved.

Originality/value

The present results are original and new for the oblique stagnation-point flow of a nanofluid past a shrinking sheet. Therefore, this study would be important for the researchers working in the relatively new area of nanofluids in order to become familiar with the flow behavior and properties of such nanofluids.

Details

International Journal of Numerical Methods for Heat & Fluid Flow, vol. 26 no. 1
Type: Research Article
ISSN: 0961-5539

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Article
Publication date: 31 January 2020

Petra Kumi, Stephanie A. Martin, Vadim V. Yakovlev, Martin S. Hilario, Brad W. Hoff and Ian M. Rittersdorf

The paper introduces and illustrates the use of numerical models for the simulation of electromagnetic and thermal processes in an absorbing ceramic layer (susceptor) of a…

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Abstract

Purpose

The paper introduces and illustrates the use of numerical models for the simulation of electromagnetic and thermal processes in an absorbing ceramic layer (susceptor) of a new millimeter-wave (MMW) heat exchanger. The purpose of this study is to better understand interaction between the MMW field and the susceptor, choose the composition of the ceramic material and help design the physical prototype of the device.

Design/methodology/approach

A simplified version of the heat exchanger comprises a rectangular block of an aluminum nitride (AlN) doped with molybdenum (Mo) that is backed by a thin metal plate and irradiated by a plane MMW. The coupled electromagnetic-thermal problem is solved by the finite-difference time-domain (FDTD) technique implemented in QuickWave. The FDTD model is verified by solving the related electromagnetic problem by the finite element simulator COMSOL Multiphysics. The computation of dissipated power and temperature is based on experimental data on temperature-dependent dielectric constant, loss factor, specific heat and thermal conductivity of the AlN:Mo composite. The non-uniformity of patterns of dissipated power and temperature is quantified via standard-deviation-based metrics.

Findings

It is shown that with the power density of the plane wave on the block’s front face of 1.0 W/mm2, at 95 GHz, 10 × 10 × 10-mm blocks with Mo = 0.25 – 4% can be heated up to 1,000 °C for 60-100 s depending on Mo content. The uniformity of the temperature field is exceptionally high – in the course of the heating, temperature is evenly distributed through the entire volume and, in particular, on the back surface of the block. The composite producing the highest level of total dissipated power is found to have Mo concentration of approximately 3%.

Research limitations/implications

In the electromagnetic model, the heating of the AlN:Mo samples is characterized by the volumetric patterns of density of dissipated power for the dielectric constant and the loss factor corresponding to different temperatures of the process. The coupled model is run as an iterative procedure in which electromagnetic and thermal material parameters are upgraded in every cell after each heating time step; the process is then represented by a series of thermal patterns showing time evolution of the temperature field.

Practical implications

Determination of practical dimensions of the MMW heat exchanger and identification of material composition of the susceptor that make operations of the device energy efficient in the required temperature regime require and expensive experimentation. Measurement of heat distribution on the ceramic-metal interface is a practically challenging task. The reported model is meant to be a tool assisting in development of the concept and supporting system design of the new MMW heat exchanger.

Originality/value

While exploitation of a finite element model (e.g. in COMSOL Multiphysics environment) of the scenario in question would require excessive computational resources, the reported FDTD model shows operational capabilities of solving the coupled problem in the temperature range from 20°C to 1,000°C within a few hours on a Windows 10 workstation. The model is open for further development to serve in the ongoing support of the system design aiming to ease the related experimental studies.

Details

COMPEL - The international journal for computation and mathematics in electrical and electronic engineering , vol. 39 no. 2
Type: Research Article
ISSN: 0332-1649

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Article
Publication date: 1 April 2003

Y.L. Wang, A.F. Carroll, J.D. Smith, Y. Cho, R.J. Bacher, D.K. Anderson, J.C. Crumpton and C.R.S. Needes

Substrates with high thermal conductivity continue to be in great demand for their ability to enable smaller and denser high power circuits. BeO has been used for this…

Abstract

Substrates with high thermal conductivity continue to be in great demand for their ability to enable smaller and denser high power circuits. BeO has been used for this purpose for many years with thick film materials. However, due to health and environmental concerns with BeO, many manufacturers feel compelled to switch to alternative substrates. This paper will discuss a thick film system consisting of conductors, dielectric, and resistors developed specifically for use with the most likely alternative, AlN substrates. This system will soon find broad use in applications such as power resistors for telecom, optoelectronic submounts, and high‐power automotive applications.

Details

Microelectronics International, vol. 20 no. 1
Type: Research Article
ISSN: 1356-5362

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Article
Publication date: 2 January 2018

Wei Qiang Lim, Mutharasu Devarajan and Shanmugan Subramani

This paper aims to study the influence of the Cu-Al2O3 film-coated Cu substrate as a thermal interface material (TIM) on the thermal and optical behaviour of the…

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Abstract

Purpose

This paper aims to study the influence of the Cu-Al2O3 film-coated Cu substrate as a thermal interface material (TIM) on the thermal and optical behaviour of the light-emitting diode (LED) package and the annealing effect on the thermal and optical properties of the films.

Design/methodology/approach

A layer-stacking technique has been used to deposit the Cu-Al2O3 films by means of magnetron sputtering, and the annealing process was conducted on the synthesized films.

Findings

In this paper, it was found that the un-annealed Cu-Al2O3–coated Cu substrate exhibited low value of thermal resistance compared to the bare Cu substrate and to the results of previous works. Also the annealing effect does not have a significant impact on the changes of properties of the films.

Research limitations/implications

It is deduced that the increase of the Cu layer thickness can further improve the thermal properties of the deposited film, which can reduce the thermal resistance of the package in system-level analysis.

Practical implications

The paper suggested that the Cu-Al2O3–coated Cu substrate can be used as alternative TIM for the thermal management of the application of LEDs.

Originality value

In this paper, the Cu substrate has been used as the substrate for the Cu-Al2O3 films, as the Cu substrate has higher thermal conductivity compared to the Al substrate as shown in previous work.

Details

Microelectronics International, vol. 35 no. 1
Type: Research Article
ISSN: 1356-5362

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Article
Publication date: 18 January 2013

Chang Keun Lee, Jung Keun Ahn, Cheul Ro Lee, Daesuk Kim and Byung Joon Baek

The purpose of this paper is to investigate the thermal behaviors of high power LED packages to enhance the thermal performances of low temperature co‐fired ceramic chip…

Abstract

Purpose

The purpose of this paper is to investigate the thermal behaviors of high power LED packages to enhance the thermal performances of low temperature co‐fired ceramic chip on board (LTCC‐COB) package. Thermal analysis demonstrated an improved LTCC‐COB package design that is comparable to a metal lead frame package with low thermal resistance.

Design/methodology/approach

The LED device developed in this study is a LTCC package mounted directly on the metal PCB. A numerical simulation was performed to investigate the thermal characteristics of the LED module using the finite volume method, which is embedded in commercial software (Fluent V.6.3). Thermal resistance and temperature measurement validate the simulated results.

Findings

The effect of the thickness of the die attach material on the thermal resistance was dominant due to low thermal conductivity, and the junction temperature decreased significantly with slight increases in thermal conductivity, especially when the value was less than 5 W/mK. The results reveal that the thermal resistance of MCPCB is about 49 per cent‐58 per cent of the junction to board thermal resistance. The thermal model results showed good agreement with experimental results.

Originality/value

The developed model overcomes the large thermal resistance of a conventional LTCC package for high power LED module. The extensive results have demonstrated an improved thermal design, optimal dimensions of each component and boundary conditions for high power LTCC‐COB type package.

Details

Microelectronics International, vol. 30 no. 1
Type: Research Article
ISSN: 1356-5362

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