Calculation limits of the homogeneous effective thermal conductivity approach in modeling of printed circuit board

Nguyen, Minh-Nhat; Monier-Vinard, Eric; Laraqi, Najib; Dia, Cheikh-Tidiane; Bissuel, Valentin

doi:10.1109/therminic.2014.6972484

Cited by 7 publications

(4 citation statements)

References 6 publications

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“…The errors on the sensitive temperature are really difficult to handle. Besides, those errors will be magnified for smaller packages (Nguyen et al , 2014; Monier-Vinard et al , 2015).…”

Section: Lumped Modeling Of Multi-layered Pwbsmentioning

confidence: 99%

State of the art of thermal characterization of electronic components using computational fluid dynamic tools

Monier-Vinard

Rogié

Bissuel

et al. 2017

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Purpose Latest Computational Fluid Dynamics (CFDs) tools allow modeling more finely the conjugate thermo-fluidic behavior of a single electronic component mounted on a Printed Wiring Board (PWB). A realistic three-dimensional representation of a large set of electric copper traces of its composite structure is henceforth achievable. The purpose of this study is to confront the predictions of the fully detailed numerical model of an electronic board to a set of experiment results to assess their relevance. Design/methodology/approach The present study focuses on the case of a Ball Grid Array (BGA) package of 208 solder balls that connect the component electronic chip to the Printed Wiring Board. Its complete geometrical definition has to be coupled with a realistic board layers layout and a fine description of their numerous copper traces to appropriately predict the way the heat is spread throughout that multi-layer composite structure. The numerical model computations were conducted on four CFD software then compare to experiment results. The component thermal metrics for single-chip packages are based on the standard promoted by the Joint Electron Device Engineering Council (JEDEC), named JESD-51. The agreement of the numerical predictions and measurements has been done for free and forced convection. Findings The present work shows that the numerical model error is lower than 2 per cent for various convective boundary conditions. Moreover, the establishment of realistic numerical models of electronic components permits to properly apprehend multi-physics design issues, such as joule heating effect in copper traces. Moreover, the practical modeling assumptions, such as effective thermal conductivity calculation, used since decades, for characterizing the thermal performances of an electronic component were tested and appeared to be tricky. A new approach based on an effective thermal conductivity matrix is investigated to reduce computation time. The obtained numerical results highlight a good agreement with experimental data. Research limitations/implications The study highlights that the board three-dimensional modeling is mandatory to properly match the set of experiment results. The conventional approach based on a single homogenous layer using effective thermal conductivity calculation has to be banned. Practical implications The thermal design of complex electronic components is henceforth under increasing control. For instance, the impact of gold wire-bonds can now be investigated. The three-dimensional geometry of sophisticated packages, such as in BGA family, can be imported with all its internal details as well as those of its associated test board to build a realistic numerical model. The establishment of behavioral models such as DELPHI Compact Thermal Models can be performed on a consistent three-dimensional representation with the aim to minimize computation time. Originality/value The study highlights that multi-layer copper trace plane discretization could be used to strongly reduce computation time while conserving a high accuracy level.

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“…The errors on the sensitive temperature are really difficult to handle. Besides, those errors will be magnified for smaller packages (Nguyen et al , 2014; Monier-Vinard et al , 2015).…”

Section: Lumped Modeling Of Multi-layered Pwbsmentioning

confidence: 99%

State of the art of thermal characterization of electronic components using computational fluid dynamic tools

Monier-Vinard

Rogié

Bissuel

et al. 2017

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“…Numerous theoretical works in the literature deal with the problems of electronic cooling to help a designer address their ceaseless needs (Bagnall et al , 2014; Vintrou et al , 2009, 2012; Maranzana et al , 2002; Ditri, 2009; Muzychka et al , 2006; Ellison, 2003; Rinaldi, 2002; Gholami and Bahrami, 2014). Based on these academic approaches, a set of solutions for a fast evaluation of the temperature profile of a set of N-constitutive cross-plane layers was established (Monier-Vinard et al , 2013, 2015; Nguyen et al , 2014). The current approach focuses on the impact of the interlayer thermal resistance on the behaviour of external heating sources cooled by conduction (Sarua et al , 2007; Ghalambor et al , 2013; Muzychka et al , 2013).…”

Section: Initial Status Of Analytical Modelmentioning

confidence: 99%

Practical analytical steady-state temperature solution for annealed pyrolytic graphite heat spreader

Nguyen¹,

Monier-Vinard

Laraqi³

et al. 2017

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Purpose The purpose of this paper is to supply an analytical steady-state solution to the heat transfer equation permitting to fast design investigation. The capability to efficiently transfer the heat away from high-powered electronic devices is a ceaseless challenge. More than ever, the aluminium or copper heat spreaders seem less suitable for maintaining the component sensitive temperature below manufacturer operating limits. Emerging materials, such as annealed pyrolytic graphite (APG), have proposed a new alternative to conventional solid conduction without the gravity dependence of a heat-pipe solution. Design/methodology/approach An APG material is typically sandwiched between a pair of aluminium sheets to compose a robust graphite-based structure. The thermal behaviour of that stacked structure and the effect of the sensitivity of the design parameters on the effective thermal performances is not well known. The ultrahigh thermal conductivity of the APG core is restricted to in-plane conduction and can be 200 times higher than its through-the-thickness conductivity. So, a lower-than-anticipated cross-plane thermal conductivity or a higher-than-anticipated interlayer thermal resistance will compromise the component heat transfer to a cold structure. To analyse the sensitivity of these parameters, an analytical model for a multi-layered structure based on the Fourier series and the superposition principle was developed, which allows predicting the temperature distribution over an APG flat-plate depending on two interlayer thermal resistances. Findings The current work confirms that the in-plane thermal conductivity of APG is among the highest of any conduction material commonly used in electronic cooling. The analysed case reveals that an effective thermal conductivity twice as higher than copper can be expected for a thick APG sheet. The relevance of the developed analytical approach was compared to numerical simulations and experiments for a set of boundary conditions. The comparison shows a high agreement between both calculations to predict the centroid and average temperatures of the heating sources. Further, a method dedicated to the practical characterization of the effective thermal conductivity of an APG heat-spreader is promoted. Research limitations/implications The interlayer thermal resistances act as dissipation bottlenecks which magnify the performance discrepancy. The quantification of a realistic value is more than ever mandatory to assess the APG heat-spreader technology. Practical implications Conventional heat spreaders seem less suitable for maintaining the component-sensitive temperature below the manufacturer operating limits. Having an in-plane thermal conductivity of 1,600 W.m−1.K−1, the APG material seems to be the next paradigm for solving endless needs of a thermal designer. Originality/value This approach is a practical tool to tailor sensitive parameters early to select the right design concept by taking into account potential thermal issues, such as the critical interlayer thermal resistance.

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“…Many theoretical and empirical models have been defined to estimate the effective thermal conductivity of a composite solid mixture [18]. Moreover, when the source PCB size ratio is below 0.1, the conventional concept of a homogenous single layer model that lumped the layers of the board must be given up [19] and the N-layer structure kept.…”

Section: Test Board Characteristicsmentioning

confidence: 99%

Thermal modeling of multi-shape heating sources on n-layer electronic board

et al. 2017

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The present work completes the toolbox of analytical solutions that deal with resolving steady-state temperatures of a multi-layered structure heated by one or many heat sources. The problematic of heating sources having non-rectangular shapes is addressed to enlarge the capability of analytical approaches. Moreover, various heating sources could be located on the external surfaces of the sandwiched layers as well as embedded at interface of its constitutive layers. To demonstrate its relevance, the updated analytical solution has been compared with numerical simulations on the case of a multi-layered electronic board submitted to a set of heating source configurations. The comparison shows a high agreement between analytical and numerical calculations to predict the centroid and average temperatures. The promoted analytical approach establishes a kit of practical expressions, easy to implement, which would be cumulated, using superposition principle, to help electronic designers to early detect component or board temperatures beyond manufacturer limit. The ability to eliminate bad concept candidates with a minimum of setup , relevant assumptions and low computation time can be easily achieved.

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Calculation limits of the homogeneous effective thermal conductivity approach in modeling of printed circuit board

Cited by 7 publications

References 6 publications

State of the art of thermal characterization of electronic components using computational fluid dynamic tools

State of the art of thermal characterization of electronic components using computational fluid dynamic tools

Practical analytical steady-state temperature solution for annealed pyrolytic graphite heat spreader

Thermal modeling of multi-shape heating sources on n-layer electronic board

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