0

Full Content is available to subscribers

Subscribe/Learn More  >

Voiding and Thermal Resistance Modeling and Characterization for a QFN Assembly

[+] Author Affiliations
Harish Gadepalli, Rangaraj Dhanasekaran, S. Manian Ramkumar

Rochester Institute of Technology, Rochester, NY

Tim Jensen, Ed Briggs

Indium Corporation, Clinton, NY

Paper No. IMECE2010-38391, pp. 487-495; 9 pages
doi:10.1115/IMECE2010-38391
From:
  • ASME 2010 International Mechanical Engineering Congress and Exposition
  • Volume 4: Electronics and Photonics
  • Vancouver, British Columbia, Canada, November 12–18, 2010
  • Conference Sponsors: ASME
  • ISBN: 978-0-7918-4428-1
  • Copyright © 2010 by ASME

abstract

Quad Flatpack No lead (QFN) packages have become a popular choice in electronics packaging due to its small form factor. They are also gaining rapid industry acceptance because of its excellent thermal and electrical performance. The bottom side of the QFN package has a large thermal pad. This exposed die attach pad effectively conducts heat to the PCB and also provides a stable ground connection. Effective soldering of this surface to the pad on the PCB is required for good thermal dissipation and component functionality. The exposed thermal pad presents various challenges during the surface mount assembly process. One major challenge is solder void formation. Voids are primarily formed due to the entrapment of volatiles in flux outgassing during the reflow process. The primary objective of this study is to determine optimal parameters to minimize void formation in QFN packages (QFN16, QFN20, QFN28, QFN32 and QFN44), specifically the reflow profile, lead-free solder paste and stencil aperture opening for the thermal pad. A systematic Design of Experiments (DOE) based approach was used to arrive at conclusions, using the ratio of void volume on the thermal pad to the actual volume of solder paste printed, as the response variable. A theoretical thermal resistance response variable was also modeled to analyze the DOE parameters and the conclusions were similar to the void model. Various graphs are presented to understand the impact of different parameters. Interaction graphs are used to determine optimal settings for each parameter. A regression equation for relationship between the factors and the void volume is identified to predict void volumes for any given component, paste volume and paste transfer efficiency.

Copyright © 2010 by ASME

Figures

Tables

Interactive Graphics

Video

Country-Specific Mortality and Growth Failure in Infancy and Yound Children and Association With Material Stature

Use interactive graphics and maps to view and sort country-specific infant and early dhildhood mortality and growth failure data and their association with maternal

NOTE:
Citing articles are presented as examples only. In non-demo SCM6 implementation, integration with CrossRef’s "Cited By" API will populate this tab (http://www.crossref.org/citedby.html).

Some tools below are only available to our subscribers or users with an online account.

Related Content

Customize your page view by dragging and repositioning the boxes below.

Related eBook Content
Topic Collections

Sorry! You do not have access to this content. For assistance or to subscribe, please contact us:

  • TELEPHONE: 1-800-843-2763 (Toll-free in the USA)
  • EMAIL: asmedigitalcollection@asme.org
Sign In