Interrogation of system state for damage assessment in lead-free electronics subjected to thermo-mechanical loads

2008 ◽  
Author(s):  
Pradeep Lall ◽  
Chandan Bhat ◽  
Madhura Hande ◽  
Vikrant More ◽  
Rahul Vaidya ◽  
...  
Keyword(s):  
Damage Assessment ◽  
Lead Free ◽  
System State ◽  
Mechanical Loads

Prognostication of system-state in lead-free electronics equipment under cyclic and steady-state thermo-mechanical loads

2009 ◽  
Vol 49 (8) ◽  
pp. 825-838 ◽  
Author(s):  
Pradeep Lall ◽  
Madhura Hande ◽  
Chandan Bhat ◽  
Vikrant More ◽  
Rahul Vaidya
Keyword(s):  
Steady State ◽  
Lead Free ◽  
System State ◽  
Mechanical Loads

RELIABILITY EVALUATION OF BGA SOLDER JOINTS DURING ACCELERATED LIFE TEST

2006 ◽  
Vol 20 (25n27) ◽  
pp. 4553-4558
Author(s):  
OUK SUB LEE ◽  
NO HOON MYOUNG ◽  
DONG HYEOK KIM ◽  
MAN JAE HUR ◽  
SI WOON HWANG
Keyword(s):  
Solder Joint ◽  
Thermal Cycling ◽  
Solder Joints ◽  
Coefficient Of Thermal Expansion ◽  
Accelerated Life Test ◽  
Lead Free ◽  
Lead Free Solder ◽  
Metal Fatigue ◽  
Mechanical Loads ◽  
Free Solder

The use of BGA (Ball Grid Array) interconnects utilizing the lead-free solder joint has grown rapidly because of its small volume and diversity of application. Thus, it requires the continuous quantification and refinement of lead-free solder joint reliability. The lead-free solder creep and cyclically applied mechanical loads cause metal fatigue on the lead-free solder joint which inevitably leads to an electrical discontinuity. In the field application, BGA solder joints experience mechanical loads during temperature changes caused by power up/down events as the result of the CTE (Coefficient of Thermal Expansion) mismatch between the substrate and the Si die. In this paper, extremely small resistance changes at joint area corresponding to through-cracks generated by thermal fatigue were measured. In this way, the failure was defined in terms of anomalous changes in electrical resistance of the joint. Furthermore the reliability of BGA solder joints in thermal cycling is evaluated by using the modified coffin-Manson criterion which may define and distinguish failure. Any change in circuit resistance according to the accumulated damage induced by the thermal cycling in the joint was recorded and evaluated in order to quantitate reliability of solder joint.

Methodologies for System-State Interrogation for Prognostication of Electronics Under Thermo-Mechanical Loads

2007 ◽  
Author(s):  
Pradeep Lall ◽  
Madhura Hande ◽  
Chandan Bhat ◽  
Jeff Suhling
Keyword(s):  
Health Monitoring ◽  
Least Squares Method ◽  
Residual Life ◽  
Electronic System ◽  
Minimal Risk ◽  
Leading Indicators ◽  
System State ◽  
Electronic Warfare ◽  
Mechanical Loads ◽  
Marquardt Algorithm

Methodologies for prognostication and health monitoring can significantly impact electronic reliability for applications in which even minimal risk of failure may be unbearable. Presently, health monitoring approaches such as the built-in self-test (BIST) are based on reactive failure diagnostics and unable to determine residual-life or estimate residual-reliability [Allen 2003, Drees 2004, Gao 2002, Rosenthal 1990]. Prognostics health-monitoring (PHM) approach presented in this paper is different from state-of-art diagnostics and resides in the pre-failure-space of the electronic-system, in which no macro-indicators such as cracks or delamination exist. Applications for the presented PHM framework include, consumer applications such as automotive safety systems including front and rear impact protection system, chassis-control systems, x-by-wire systems; and defense applications such as avionics systems, naval electronic warfare systems. The presented PHM methodologies enable the estimation of prior damage in deployed electronics by interrogation of the system state. The presented methodologies will trigger repair or replacement, significantly prior to failure. The approach involves the use of condition monitoring devices which can be interrogated for damage proxies at finite time-intervals. The system’s residual life is computed based on residual-life computation algorithms. Previously, Lall, et. al. [2004, 2005, 2006] have developed several leading indicators of failure. In this paper a mathematical approach has been presented to calculate the prior damage in electronics subjected to cyclic and isothermal thermomechanical loads. Electronic components operating in a harsh environment may be subjected to both temperature variations in addition to thermal aging during use-life. Data has been collected for leading indicators of failure for 95.5Sn4Ag0.5Cu first-level interconnects under both single and sequential application of cyclic and isothermal thermo-mechanical loads. Methodology for the determination of prior damage history has been presented using non-linear least-squares method based interrogation techniques. The methodology presented used the Levenberg-Marquardt Algorithm. Test vehicle includes various area-array packaging architectures soldered on Immersion Ag finish, subjected to thermal cycling in the range of −40°C to 125°C and isothermal aging at 125°C.

Prognostication of Residual Life and Latent Damage Assessment in Lead-Free Electronics Under Thermomechanical Loads

2011 ◽  
Vol 58 (7) ◽  
pp. 2605-2616 ◽  
Author(s):  
Pradeep Lall ◽  
Chandan Bhat ◽  
Madhura Hande ◽  
Vikrant More ◽  
Rahul Vaidya ◽  
...  
Keyword(s):  
Damage Assessment ◽  
Residual Life ◽  
Lead Free
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