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RESEARCH PAPERS

Reliability of BGA and CSP on Metal-Backed Printed Circuit Boards in Harsh Environments

[+] Author and Article Information
Pradeep Lall1

Department of Mechanical Engineering, Department of Industrial and Systems Engineering, Center for Advanced Vehicle Electronics, Auburn University, Auburn, AL 36849lall@eng.auburn.edu

Nokibul Islam, John Evans, Jeff Suhling

Department of Mechanical Engineering, Department of Industrial and Systems Engineering, Center for Advanced Vehicle Electronics, Auburn University, Auburn, AL 36849

1

Corresponding author.

J. Electron. Packag 129(4), 382-390 (Mar 07, 2007) (9 pages) doi:10.1115/1.2804086 History: Received December 29, 2004; Revised March 07, 2007

Increased use of sensors and controls in automotive applications has resulted in significant emphasis on the deployment of electronics directly mounted on the engine and transmission. Increased shock, vibration, and higher temperatures necessitate the fundamental understanding of damage mechanisms, which will be active in these environments. Electronics typical of office benign environments uses FR-4 printed circuit boards (PCBs). Automotive applications typically use high glass-transition temperature laminates such as FR4-06 glass∕epoxy laminate material (Tg=164.9°C). In application environments, metal backing of printed circuit boards is being targeted for thermal dissipation, mechanical stability, and interconnections reliability. In this study, the effect of metal-backed boards on the interconnect reliability has been evaluated. Previous studies on electronic reliability for automotive environments have addressed the damage mechanics of solder joints in plastic ball-grid arrays on non-metal-backed substrates (Lall, 2003, “Model for BGA and CSP in Automotive Underhood Environments  ,” Electronic Components and Technology Conference, New Orleans, LA, May 27–30, pp. 189–196;Syed, A. R., 1996, “Thermal Fatigue Reliability Enhancement of Plastic Ball Grid Array (PBGA) Packages  ,” Proceedings of the 1996 Electronic Components and Technology Conference, Orlando, FL, May 28–31, pp. 1211–1216;Evans, 1997, “PBGA Reliability for Under-the-Hood Automotive Applications  ,” Proceedings of InterPACK ’97, Kohala, HI, Jun. 15–19, pp. 215–219;Mawer, 1999, “Board-Level Characterization of 1.0 and 1.27mm Pitch PBGA for Automotive Under-Hood Applications  ,” Proceedings of the 1999 Electronic Components and Technology Conference, San Diego, CA, Jun. 1–4, pp. 118–124) and ceramic ball-grid arrays (BGAs) on non-metal-backed substrates (Darveaux, R., and Banerji, K., 1992, “Constitutive Relations for Tin-Based Solder Joints  ,” IEEE Trans-CPMT-A, Vol. 15, No. 6, pp. 1013–1024;Darveaux, 1995, “Reliability of Plastic Ball Grid Array Assembly  ,” Ball Grid Array Technology, Lau, J., ed., McGraw-Hill, New York, pp. 379–442;Darveaux, R., 2000, “Effect of Simulation Methodology on Solder Joint Crack Growth Correlation  ,” Proceedings of 50th ECTC, May, pp. 1048–1058). Delamination of PCBs from metal backing has also been investigated. The test vehicle is a metal-backed FR4-06 laminate. The printed circuit board has an aluminum metal backing, attached with pressure sensitive adhesive (PSA). Component architectures tested include plastic ball-grid array devices, C2BGA devices, QFN, and discrete resistors. Reliability of the component architectures has been evaluated for HASL. Crack propagation and intermetallic thickness data have been acquired as a function of cycle count. Reliability data have been acquired on all these architectures. Material constitutive behavior of PSA has been measured using uniaxial test samples. The measured constitutive behavior has been incorporated into nonlinear finite element simulations. Predictive models have been developed for the dominant failure mechanisms for all the component architectures tested.

Copyright © 2007 by American Society of Mechanical Engineers
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References

Figures

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Figure 1

BGA and chip resistor test vehicle

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Figure 2

Images of uncycled 15mm BGA cross section: (a) underfilled BGA with metal back and (b) solder interconnect

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Figure 3

Test board thermal cycle (−40–125°C).

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Figure 4

Effect of aluminum metal backing on reliability of 2512 resistors with arlon and PSA adhesives

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Figure 5

Weibull plot of 1% failure for BGA component

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Figure 6

2512 quarter symmetry 3D mesh plot on metal-backed board

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Figure 7

3D quarter symmetry finite-element mesh for (a) C2BGA assembly and (b) 15mm BGA

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Figure 8

Simultaneous crack propagation top and bottom of the solder joint, C2BGA

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Figure 9

Image of crack initiation, corner ball, 15mm BGA

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Figure 10

27mm BGA solder joint crack propagation or growth on metal-backed boards at various levels of thermal cycling (−40–125°C)

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Figure 11

Typical image of crack Initiation and propagation of 2512 chip resistor solder joint

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Figure 12

Cross section of a completely cracked 2512 resistor

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Figure 13

Crack propagation data for 15mm BGA, 27mm BGA, and 16mm C2BGA

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Figure 14

Crack propagation data for 15mm and 27mm BGA thermal balls

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Figure 15

Crack propagation data for 2512 and 1225 chip resistor

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Figure 16

Typical intermetallic formation after 625cycles(−40–125°C).

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Figure 17

Comparative crack initiation∕unit inelastic strain energy between metal∕nonmetal boards

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Figure 18

Comparative crack growth rate∕unit inelastic strain energy between metal∕nonmetal boards

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