Research Papers

Embarked Quad Flat Nonlead 16, 32, and 64 Electronic Devices Subjected to Free Convection: Influence of the Adhesive Paste on the Junction Temperature

[+] Author and Article Information
Abderrahmane Baïri

University of Paris,
Laboratoire Thermique Interfaces Environnement,
50, rue de Sèvres,
Ville d’Avray F-92410, France;
Association Aéronautique et Astronautique de
France (The French Aeronautics and
Astronautics Society, 3AF),
3AF, 6, rue Galilée,
Paris F-75016, France
e-mails: abairi@u-paris10.fr;

Bruno Chanetz

Office National d’Etudes et de Recherches
Aérospatiales (ONERA),
Chemin de la Hunière,
BP 80100,
Palaiseau Cedex F-91123, France;
Association Aéronautique et Astronautique de
France (The French Aeronautics
and Astronautics Society, 3AF),
3AF, 6, rue Galilée,
Paris F-75016, France
e-mail: bruno.chanetz@onera.fr

J. A. Millán-García

Departamento Máquinas y Motores Térmicos,
University of the Basque Country,
Escuela de Ingeniería de Gipuzkoa,
ENEDI Research Group,
Plaza Europa 1,
San Sebastián-Donostia E-20018, Spain
e-mail: j.millan@ehu.eus

1Corresponding author.

Contributed by the Electronic and Photonic Packaging Division of ASME for publication in the JOURNAL OF ELECTRONIC PACKAGING. Manuscript received November 12, 2016; final manuscript received September 28, 2017; published online October 25, 2017. Assoc. Editor: Shi-Wei Ricky Lee.

J. Electron. Packag 139(4), 041009 (Oct 25, 2017) (5 pages) Paper No: EP-16-1124; doi: 10.1115/1.4038113 History: Received November 12, 2016; Revised September 28, 2017

The junction temperature of the quad flat nonlead (QFN) electronic devices equipping embarked assemblies may be controlled so that it does not exceed the maximum value recommended by the manufacturer. The packaging design is then important to ensure correct operation and high reliability, given the significant power generated during operation and the inclination angle of the packages during the flight. It is particularly important when thermoregulation is achieved by means of natural convection. The objective of this study is to examine the influence of the adhesive paste used to connect the Die of the QFN with its base. The study deals with three devices among the most used in the conventional arrangements: the QFN16, 32, and 64. A three-dimensional (3D) numerical solution based on the control volume formulation allows to determine their thermal behavior for generated power ranging from 0.1 to 1.0 W by steps of 0.1 W and inclination angle varying between 0 deg (horizontal position) and 90 deg (vertical position) by steps of 15 deg. A wide range of the paste’s thermal conductivity has been considered, varying between −80% and +100% of its average value, measured by means of the transient plane source (TPS) method. The numerical results confirmed by measurements show that the junction temperature strongly increases when the conductivity of the paste decreases. The temperature is moderately reduced when the paste is thermally more conductive. Relationships are proposed to calculate the junction temperature for the three considered devices, according to the generated power, the inclination angle, and the relative paste’s thermal conductivity.

Copyright © 2017 by American Society of Mechanical Engineers
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Grahic Jump Location
Fig. 5

Evolution of θ=(TJ)λp*≠1−(TJ)λp*=1 versus λp* for the QFN16, 32, and 64 packages in 0≤α≤90deg step15deg, for P=0.1, 0.5 and 1W

Grahic Jump Location
Fig. 4

Evolution of ΔT versus λp* and versus α for the (a) and (b) QFN16; (c) and (d) QFN32; (e) and (f) and QFN64; for P=0.1, 0.5 and 1W

Grahic Jump Location
Fig. 3

Evolution of rp*=(TJ)λp*≠1/(TJ)λp*=1 versus λp* for the QFN16, 32, and 64 packages

Grahic Jump Location
Fig. 1

The considered assembly: (a) the PCB, (b) details of the QFN64 device, and (c) the mesh device structure of the QFN32 device

Grahic Jump Location
Fig. 2

Typical dimensionless (a)–(c) temperature fields and velocity vectors for α = 0, 60, and 90 deg; (d) temperature distribution for the QFN32



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