High Resolution Characterization of Materials Used in Packages Through Digital Image Correlation

2013 IEEE 63rd Electronic Components and Technology Conference

Shantaram

Suhling

et al. 2013

Electronics subjected to shock and vibration may experience strain rates of 1-100 sec -1 . High strain rate data is scarce for leadfree solders at strain rates in the range of 1-100 sec -1 , typical of drop-impact, shock and vibration.A new experimental method has been developed to achieve constant strain rate in the neighborhood of 1 to 100 sec -1 during the entire deformation history. SAC105 and SAC305, which are two of the widely used leadfree alloys, have been tested at strain rates of 10, 35, 50 and 75 per sec. Effect of aging on the high strain rate properties has also been quantified by subjecting the test specimen to thermal aging for varied periods of time at various temperatures. The leadfree solders have been exposed to constant temperatures of 25°C, 50°C, 75°C, 100°C and 125°C for 1 day, 30 days and 60 days prior to high strain-rate test. Full-field strain in the specimen has been measured using high speed imaging at frame rates up to 75,000 fps in combination with digital image correlation. The cross-head velocity has been measured prior-to, during, and after deformation to ensure the constancy of cross-head velocity. Experimental data for the unaged and the aged specimen has been fit to the non-linear Ramberg-Osgood model using two methods.

Section: Introductionmentioning

confidence: 99%

Effect of aging on the high strain rate mechanical properties of SAC105 and SAC305 leadfree alloys

2013 IEEE 63rd Electronic Components and Technology Conference

Shantaram

Suhling

et al. 2013

“…The technique involves the application of speckle pattern on the surface of the printed circuit board assembly and tracking a geometric point on the speckle patterned surface before and after loading and using it to compute both in-plane as well as out-of-plane deformations in the structures. Displacement field quantities are obtained by tracking a geometric point before and after deformation [Zhou 2001, Amodio 2003, Srinivasan 2005, Kehoe 2006c , 2008 ]. The tracking is achieved using digital image processing of speckle pattern on the specimen surface.…”

Section: Measurement Of Package and Circuit Board Deformationmentioning

confidence: 99%

Board trace fatigue models and design guidelines for electronics under shock-impact

2010 12th IEEE Intersociety Conference on Thermal and Thermomechanical Phenomena in Electronic Systems

Angral

Suhling

2010

Driven by the trends towards miniaturization and increased functionality, modern electronic systems are being built into more intricate and smaller packages.The mechanical robustness of these smaller and more complex packages is of great concern to the electronics industry. With advances in packaging technology, more reliable interconnects are being designed as a result of which the accountability for failure shifts to copper traces which form the primary failure mode. Previous researchers have addressed copper trace fatigue reliability [Farley 2009] and existence of copper-trace failures in drop-shock [Tee 2009]. This paper addresses the need for life prediction models for PWB copper traces in shock and vibration environments. The study focuses on high cycle fatigue of copper traces which is simulated by subjecting the PWB to vibrations in first mode until failure. Owing to the complexity of the test vehicle, global-local finite element models were developed for simulating the board response. The study addresses the need for empirical rules for trace layout on the PWB which ensure maximum reliability. The effect of trace orientation, trace-pad fillet angle and trace width on its reliability has been investigated. Using Digital Image Correlation based strain responses and Finite Element Model based stress responses, mathematical models for damage accumulation and life prediction of copper traces have been formulated and validated with experimental failure statistics.

“…DIC has been used for shock‐deformation in electronic assemblies by tracking the speckle pattern in small regions called subsets during a transient event namely drop – impact in conjunction with high speed cameras. DIC is an optical method to measure full field deformation on the surface of an object based on tracking a geometric point before and after deformation and using it to calculate the displacement field [34, 36, 43, 45]. The undeformed and deformed images are called the original image and deformed image respectively.…”

Section: Dic For Transient Dynamic Eventsmentioning

confidence: 99%

“…DIC enables full field strain and displacement measurement during a transient event namely shock and drop‐impact in comparison to a gage which measures strain only at localised points on the specimen. DIC has been used in electronic industry to study dynamic response of printed circuit assemblies of mobile phones [27–29], material characterisation [30–33], stresses and strain in flip‐chip die under thermal loading [34], fracture toughness of underfill/chip interface due to temperature and ageing conditions [35], stresses in solder interconnects of BGA packages under thermal loading [36–42], and material characterisation under thermal loading [43, 44].…”

Section: Introductionmentioning

confidence: 99%

Damage Progression Using Speckle‐Correlation and High‐Speed Imaging for Survivability of Leadfree Packaging Under Shock

Iyengar

Shantaram

et al. 2009

Strain

In this paper, a methodology to predict failure of electronics under shock and vibration loads has been investigated. Reliability prediction models have been developed using optical feature extraction techniques for 6-leadfree solder alloy systems. Solder alloy systems investigated include, Sn1Ag0.5Cu, Sn3Ag0.5Cu, Sn0.3Ag0.7Cu, Sn0.3Ag0.7Cu0.1Bi, 96.5Sn3.5Ag. Previously, Digital Image Correlation (DIC) has been used for measurement of thermally-induced deformation and material characterisation. In this paper, DIC has been used for transient dynamic measurements, and optical feature extraction. Board assemblies have been subjected to shock-impact in various orientations including the zero-degree JEDEC drop and the vertical free-drop. Transient deformation has been measured using both DIC and the strain gages. Measurements have been taken on both the package and the board side of the assemblies. Accuracy of high-speed optical measurement has been compared with that from discrete strain gages. Package architectures examined include-flex ball-grid arrays, tape-array ball-grid arrays, and metal lead-frame packages. Explicit finite-element models have been developed and correlated with experimental data. Three models were developed: smeared property models: Timoshenko-beam models: and explicit sub-models. The potential of damage identification and tracking for various solder alloys has been investigated. Data on the identification of damage proxies for competing failure mechanisms at the copper-to-solder, solder-to-printed circuit board, and copper-to-package substrate has been presented. Design envelopes have been developed based on Statistical Pattern Recognition (SPR). The design-envelope is intended for component integration to ensure survivability in shock and vibration environments at a user-specified confidence level.