NDLI: Causes of Degradation of Thermal Performance of Ball Grid Arrays After Thermal Cycling

Content Provider	The American Society of Mechanical Engineers (ASME) Digital Collection
Author	Roy, W. Knight Elkady, Yasser Jeffrey, C. Suhling Lall, Pradeep
Copyright Year	2007
Abstract	The thermal performance of Ball Grid Array packages depends upon many parameters including die size, use of thermal balls, number of perimeter balls, use of underfill, and printed circuit board heat spreader and thermal via design. Thermal cycling can affect the integrity of thermal paths in and around the BGA as a result of the cracking of solder balls and delamination of the package, including at underfill interfaces. In this study, the impact of thermal cycling on the thermal performance of BGA’s was investigated and quantified. A number of test boards which included a range of the parameters cited above were experimentally examined. A baseline thermal resistance was measured for each case, which was verified with numerical thermal modeling. The boards were then subjected to thermal cycling from −40°C to 125°C. Every 250 cycles the thermal performance was measured. Packages expected to be least reliable (with large die and no underfill), showed an increase in thermal resistance after 750 thermal cycles. Further increases in thermal resistance were observed with continuous thermal cycling until solder joint failure occurred at 1250 cycles, preventing additional measurements. Finite element analysis identified critical thermal and perimeter solder balls as the most likely sites for cracking. Boards were cross-sectioned and examined for solder joint cracks and delamination to identify the cause for the observed increases in thermal resistance. Cracking was found in the critical thermal and perimeter solder balls.
Sponsorship	Electronic and Photonic Packaging Division
Starting Page	663
Ending Page	670
Page Count	8
File Format	PDF
ISBN	0791842789
DOI	10.1115/IPACK2007-33626
e-ISBN	0791838013
Volume Number	ASME 2007 InterPACK Conference, Volume 2
Conference Proceedings	ASME 2007 InterPACK Conference collocated with the ASME/JSME 2007 Thermal Engineering Heat Transfer Summer Conference
Language	English
Publisher Date	2007-07-08
Publisher Place	Vancouver, British Columbia, Canada
Access Restriction	Subscribed
Subject Keyword	Flat heat pipes Cracking (materials) Cycles Solder joints Solders Fracture (materials) Modeling Design Fracture (process) Ball-grid-array packages Printed circuit boards Thermal resistance Ball-grid-array packaging Finite element analysis Delamination Failure Lumber
Content Type	Text
Resource Type	Article

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