Numerical Heat Transfer Predictive Accuracy for an In-Line Array of Board-Mounted Plastic Quad Flat Back Components in Free Convection

[+] Author and Article Information
Valérie Eveloy1

CALCE Electronic Products and Systems Center,  University of Maryland, College Park, MD 20742veveloy@calce.umd.edu

Peter Rodgers

CALCE Electronic Products and Systems Center,  University of Maryland, College Park, MD 20742rodgers@calce.umd.edu

M. S. Hashmi

School of Mechanical and Manufacturing Engineering,  Dublin City University, Collins Avenue, Dublin 9, Irelandsaleem.hashmi@dcu.ie


Corresponding author.

J. Electron. Packag 127(3), 245-254 (Jun 26, 2004) (10 pages) doi:10.1115/1.1938988 History: Received January 21, 2003; Revised June 26, 2004

Numerical predictive accuracy is assessed for board-mounted electronic component heat transfer in free convection, using a computational fluid dynamics code dedicated to the thermal analysis of electronic equipment. This is achieved by comparing numerical predictions with experimental measurements of component junction temperature and component-PCB surface temperature, measured using thermal test chips and infrared thermography, respectively. The printed circuit board (PCB) test vehicle considered is populated with fifteen 160-lead PQFP components generating a high degree of component thermal interaction. Component numerical modeling is based on vendor-specified, nominal package dimensions and material thermophysical properties. To permit both the modeling methodology applied and solver capability to be carefully evaluated, test case complexity is incremented in controlled steps, from individually to simultaneously powered component configurations. Component junction temperature is predicted overall to within ±5°C (7%) of measurement, independently of component location on the board. However, component thermal interaction is found not to be fully captured.

Copyright © 2005 by American Society of Mechanical Engineers
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Figure 1

Multicomponent thermal test PCB. PCB size=233×160×1.6mm. The position of each component on the PCB is identified by the lettering, A–O. Axes X-X, Y1-Y1, and Y2-Y2 denote planes for surface temperature analysis.

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Figure 2

Component internal architecture for the three thermally enhanced 160-lead PQFP package types: (a) Package type I, board locations A, K, and F–I; (b) Package type II, board location J; (c) Package type III, board locations B to E, and L–O. Package body, 28×28×3.4mm. Component board locations are defined in Fig. 1.

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Figure 3

Component numerical models: (a) Package type I; (b) Package type II; (c) Package type III.

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Figure 4

Component-PCB numerical models: (a) Single board-mounted component at position H; (b) Individually powered configurations, components (A–C, F–H, E–M); (c) Simultaneously powered configuration. Unmarked computational domain boundaries are free-air boundaries. Gravity vector acts in the (−y) direction.

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Figure 5

Comparison of measured and predicted component-PCB surface temperature profiles for the single board-mounted component at position H: (a) Temperature profile in the span-wise direction, Fig. 1; (b) Temperature profile in the stream-wise direction, Fig. 1. Analysis planes are defined in Fig. 1, with the origin of x- and y-axes corresponding to the package center. Uncertainty in temperature measurement=±1.4°C(6).

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Figure 6

Comparison of measured and predicted component-PCB surface temperature profiles on the board noncomponent side, for the simultaneously powered PCB: (a) Component locations F to J, Plane X-X; (b) Component locations A, F, K, Plane Y1-Y1; (c) Component locations D, I, N, Plane Y2-Y2. Analysis planes defined in Fig. 1. Uncertainty in temperature measurement=±1.4°C(6). (—) denotes component body location on the board component side. (⋯) Copper denotes tracking location on the board noncomponent side.




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