Correlations highlighting effects of the PCB’s Copper ratio on the free convective heat transfer for a tilted QFN32 electronic package

Hermoso

Ortega

et al. 2017

HFF

Purpose This work deals with the case of the quad flat non-lead 64 (QFN64) electronic package generating a low power range ranging from 0.01 to 0.1W. It is installed on one side of a printed circuit board (PCB) that can be inclined relative to the horizontal plane with an angle varying between 0° and 90° (horizontal and vertical positions, respectively). The surface temperature of the electronic assembly is subjected to air natural convection. Design/methodology/approach Calculations are done by means of the finite volume method for many configurations obtained by varying the generated power and the inclination angle. Findings The distribution of the surface temperature is determined on all the assembly areas (QFN and PCB). The study shows that the thermal behaviour of the electronic device is influenced by the generated power and the inclination angle. The 3D numerical survey leads to correlations allowing calculation of the average surface temperature in any part of the assembly, according to the power generated by the QFN64 and the inclination angle. Originality/value The proposed accurate correlations are original and unpublished. They optimize the thermal design of the electronic QFN64 package, which is increasingly used in many engineering fields.

Section: Introductionmentioning

confidence: 99%

Surface temperature of electronic assemblies equipped with tilted and low-powered QFN64 subjected to free convection

Hermoso

Ortega

et al. 2017

HFF

“…These values have been measured within ±3% by means of the Hot Disk TPS 2500 model [24], based on the transient plane source (TPS) method [25], with parallelepipedic samples (square side 12 mm, 4 mm thick) provided by a QFN's manufacturer. The copper network density corresponds to a Copper ratio of 5.26% (see [18]). The resulting thermal conductivity of the PCB according to its plane is of 20 Wm − 1 K −1 and 0.35 in its thickness.…”

Section: The Considered Assemblymentioning

confidence: 99%

“…Many generated power ranges (low and high ranges) varying between 0.01 and 1.0 W are considered. For these electronic assemblies, it is clearly shown [18] that the thermal conductivity of the upper copper layer of the PCB highly affects the thermal behaviour of the electronic assemblies. The results are presented by means of specific relationships.…”

Section: Introductionmentioning

confidence: 99%

Thermal state of electronic assemblies applied to smart building equipped with QFN64 device subjected to natural convection

Microelectronics Reliability

Roseiro

Martín-Garín

et al. 2017

Self Cite

The performance and reliability of electronic components and assemblies strongly depend on their thermal state. The knowledge of the temperature distribution throughout the assembly is therefore an essential element to ensure their correct operation. This is the main objective of this work that examines the case of a conventional assembly equipped with a quad flat non-lead QFN64 subjected to free convection. This active electronic package is welded on a PCB which may be inclined by an angle varying between 0°and 90°(horizontal and vertical positions respectively) and generates during its operation a high power ranging from 0.1 to 1 W. Thermoregulation of the assembly is ensured by natural convection, given its many well known advantages in this engineering field. Accurate relationships are proposed to determine the temperature on different areas of the device and the PCB. They are determined by means of a 3D numerical approach based on the finite volume method confirmed by measurements on an actual installation. These relationships allow reliability improvement of these electronic assemblies that are widely used in many engineering fields such as computing industry, mobile telephony, home automation, automotive, embarked electronics and the smart building applications considered in this work. The present survey complements a recent study which quantifies the natural convective heat transfer on the considered electronic assembly equipped with the QFN64 device, for the same power range and angle of inclination.

“…Conduction in the wire-bonded QFN version constitutes the main particularity examined in this survey. More details concerning the 3D numerical procedure adopted in this work can be found in the recent works by Baïri (2016bBaïri ( , 2016c. The calculations were made for many configurations obtained by varying the inclination angle a between 0°and 90°by steps of 15°and the generated power P between 0.01 and 0.1 W by steps of 0.01 W, corresponding to the partial operating conditions of the device.…”

Section: Hff 276mentioning

confidence: 99%

“…Cavities of various shapes are treated with many convective fluids, going from air to nanofluids (Abu-Nada, 2015;Basak and Chamkha, 2012;Basak et al, 2009;Hossain et al, 2013;Malleswaran et al, 2013;Öztop et al, 2012;Pop et al, 2003, Rashidi andShahmohamadi, 2009). Recent studies are devoted to the aerothermal phenomena and the convective heat transfer concerning assemblies equipped with 16 leads by Baïri (2015) and 32 leads by Baïri and Haddad (2016) and Baïri (2016aBaïri ( , 2016b, with and without wire-bondings. To the authors' knowledge, only the work by Baïri (2016c) quantifies the free convective heat transfer coefficient for a QFN64b generating a power varying between 0.01 and 0.1 W, but the temperature distribution on the different parts of the assembly is not presented.…”

mentioning

confidence: 99%

Numerical and experimental study of free convection on wire-bonded QFN64b electronic package

Alilat

Hocine

et al. 2017

HFF

Purpose The wire-bonded version of the quad flat non-lead with 64 leads (QFN64b) is increasingly integrated in modern arrangements, given its thermal and electrical characteristics suited for specific applications. Temperature control is thus essential for its proper operation, particularly when the heat exchange with the environment is done by natural convection. This work aims to consider a conventional assembly consisting of a large printed circuit board (PCB) on which is welded a QFN64b generating a power in the range 0.01-0.1 W. The PCB could be inclined at an angle varying between 0° and 90° (horizontal and vertical positions, respectively) according to the intended application. Design/methodology/approach The 3D numerical approach done by means of the finite volume method is complemented by thermal and electrical measurements for all the configurations numerically processed. The low deviations obtained between the calculations and the measurements validate the adopted model. These results complement recent work that considers the same assembly equipped with a tilted and low-powered QFN64 basic model subjected to free convection. Findings The surface temperature in any part of the assembly has been determined. The influence of the power generated by the device and the PCB’s inclination angle relative to the gravity field have been quantified. The work shows that the radiative heat transfer is negligible given the temperatures reached and that the thermal state of the considered assembly is different from the one equipped with the QFN64 basic model. The QFN’s temperature is lowered, while that of the PCB is increased. The temperature distribution is also different from that of assemblies equipped with other QFN models with and without wire-bonding. Originality/value The correlations proposed in this survey help optimize the thermal design of the QFN64b electronic package used in many engineering fields.