The Reliability Impact of Reballing COTS Pb-Free BGAs to Sn/Pb for Military Applications

2011 ◽  
Vol 2011 (1) ◽  
pp. 000703-000710
Author(s):  
Greg Caswell ◽  
Joelle Arnold
Keyword(s):  
Thermal Cycling ◽  
Hazardous Substances ◽  
Post Processing ◽  
Sac305 Solder ◽  
Post Process ◽  
Physical Testing ◽  
Solder Balls ◽  
Commercial Off The Shelf ◽  
Tin Silver Copper ◽  
The Cost

The electronics assembly market has experienced a material shift from lead (Pb) based solders to Pb-free solders. This is a result of the widespread adoption of Reduction of Hazardous Substances (RoHS) legislation and practices in commercial industry. As a result, it is becoming increasingly difficult to procure commercial off-the-shelf (COTS) components with tin-lead (SnPb) solder balls or finish. There are essentially three responses to the scarcity of acceptable SnPb parts: custom order, post process or adapt. Custom ordering parts with SnPb finishes negates the benefits of COTS based acquisition; however, has a reduced reliability risk because the material and processes are known. Reprocessing parts once in house saves money because the parts are COTS, but expends money and resources by performing post processing on them. Also, the additional touch labor and handling increases the risk of damaging the part. Finally, adapting to Pb-free finishes is the preferred long term approach because it preserves the cost benefits of using COTS parts and does not require post processing. It is the riskiest approach due to the lack of historical data in the DoD environment. This paper presents results regarding reballing 208 I/O Ball Grid Array (BGA) parts from tin-silver-copper (SAC305) solder to SnPb eutectic solder. It is important to understand the reliability risks associated with the reballing procedure, particularly as it relates to thermal cycling, shock and vibration environments. Three major efforts will be presented to answer these concerns. First, a survey of reballing vendors was performed to better understand the processes and variables associated with that industry. The results of that survey were used to down-select to five vendors that were used for the physical testing portion of the effort. Finally, physical testing consisting of thermal cycling, shock, and vibration was performed. The physical testing was performed on parts from the five different reballing vendors as well as native SnPb parts and native SAC305 parts. The results of these activities will be presented.

Effects of Corner/Edge Bonding and Underfill Properties on the Thermal Cycling Performance of Lead Free Ball Grid Array Assemblies

2012 ◽  
Vol 134 (1) ◽  
Author(s):  
P. Borgesen ◽  
D. Blass ◽  
M. Meilunas
Keyword(s):  
Thermal Cycling ◽  
Flip Chip ◽  
Printed Circuit Board ◽  
Ball Grid Array ◽  
Cycling Performance ◽  
Circuit Board ◽  
Lead Free ◽  
Sac305 Solder ◽  
Solder Balls ◽  
Selection Of

Underfilling will almost certainly improve the performance of an area array assembly in drop, vibration, etc. However, depending on the selection of materials, the thermal fatigue life may easily end up worse than without an underfill. This is even more true for lead free than for eutectic SnPb soldered assemblies. If reworkability is required, the bonding of the corners or a larger part of the component edges to the printed circuit board (PCB), without making contact with the solder joints, may offer a more attractive materials selection. A 30 mm flip chip ball grid array (FCBGA) component with SAC305 solder balls was attached to a PCB and tested in thermal cycling with underfills and corner/edge bonding reinforcements. Two corner bond materials and six reworkable and nonreworkable underfills with a variety of mechanical properties were considered. All of the present underfills reduced the thermal cycling performance, while edge bonding improved it by up to 50%. One set of the FCBGAs was assembled with a SnPb paste and underfilled with a soft reworkable underfill. Surprisingly, this improved the thermal cycling performance slightly beyond that of the nonunderfilled assemblies, providing up to three times better life than for those assembled with a SAC305 paste.

scholarly journals Thermal inactivation and growth potential of Listeria monocytogenes in smoked tench

2016 ◽  
Vol 5 (3) ◽  
Author(s):  
Raffaella Branciari ◽  
Andrea Valiani ◽  
Raffaella Franceschini ◽  
David Ranucci ◽  
Alessia Lupattelli ◽  
...  
Keyword(s):  
Experimental Study ◽  
Listeria Monocytogenes ◽  
Thermal Inactivation ◽  
Challenge Test ◽  
Listeria Innocua ◽  
Growth Potential ◽  
Post Processing ◽  
Colony Forming Unit ◽  
Post Process ◽  
Hygiene Measures

An experimental study for the evaluation of <em>Listeria monocytogenes</em> inactivation during a hot smoking process in tench was performed using <em>Listeria innocua</em> strains. Furthermore, the survival of <em>L. monocytogenes</em> in smoked tench was determined after post-processing in contaminated samples, evaluating the growth potential during storage. <em>L. innocua</em> was not detected after the smoking process. In the challenge test, the growth potential of <em>L. monocytogenes</em> was 5.68 log colony forming unit g<sup>−1</sup>. The results showed that hot smoking at an inner temperature around 72°C is able to eliminate the microorganism. Nevertheless, the product is able to support the growth of the pathogen if post-process contamination occurs, as the food is suitable for <em>Listeria</em> multiplication. Product recontamination should be prevented by means of appropriate application of hygiene measures.

scholarly journals On the implementation of post-processing of runoff forecast ensembles

2021 ◽  
Author(s):  
Jon Olav Skøien ◽  
Konrad Bogner ◽  
Peter Salamon ◽  
Fredrik Wetterhall
Keyword(s):  
Initial Conditions ◽  
Processing Parameters ◽  
Forecast Errors ◽  
Post Processing ◽  
Continental Scale ◽  
Post Process ◽  
Global Calibration ◽  
Calibration Methods ◽  
Verification Period ◽  
Ensemble Model Output Statistics

AbstractDifferent post-processing techniques are frequently employed to improve the outcome of ensemble forecasting models. The main reason is to compensate for biases caused by errors in model structure or initial conditions, and as a correction for under- or overdispersed ensembles. Here we use the Ensemble Model Output Statistics method to post-process the ensemble output from a continental scale hydrological model, LISFLOOD, as used in the European Flood Awareness System (EFAS). We develop a method for local calibration and interpolation of the post-processing parameters and compare it with a more traditional global calibration approach for 678 stations in Europe based on long term observations of runoff and meteorological variables. For the global calibration we also test a reduced model with only a variance inflation factor. Whereas the post-processing improved the results for the first 1-2 days lead time, the improvement was less for increasing lead times of the verification period. This was the case both for the local and global calibration methods. As the post-processing is based on assumptions about the distribution of forecast errors, we also present an analysis of the ensemble output that provides some indications of what to expect from the post-processing.

Impact of Reprocessing Technique on First Level Interconnects of Pb-Free to SnPb Reballed Area Array Flip Chip Devices

2014 ◽  
Vol 2014 (1) ◽  
pp. 000112-000116
Author(s):  
Joelle Arnold ◽  
Steph Gulbrandsen ◽  
Nathan Blattau
Keyword(s):  
Computer Tomography ◽  
Damage Accumulation ◽  
Flip Chip ◽  
Ball Grid Array ◽  
Acoustic Microscopy ◽  
Eutectic Solder ◽  
X Ray ◽  
Area Array ◽  
Solder Balls ◽  
Commercial Off The Shelf

The risk of damage caused by reballing SnPb eutectic solder balls onto a commercial off-the-shelf (COTS) active flip chip with a ball grid array (BGA) of SAC305 was studied. The effects of reballing performed by five different reballers were examined and compared. The active flip chip device selected included manufacturer specified resistance between eight (8) differential port pairs. The path resistance between these pins following reballing, as compared to an unreballed device, was used to assess damage accumulation in the package. 2-dimensional x-ray microscopy, acoustic microscopy, and x-ray computer tomography were also used to characterize the effects of reballing. These studies indicated that no measureable damage was incurred by the reballing process, implying that reballed devices should function as well as non-reballed devices in the same application.

Design and Direct Assembly of 2.5D/3D Rigid Silicon Interposer on PCB

2014 ◽  
Vol 2014 (1) ◽  
pp. 000783-000786 ◽  
Author(s):  
Farhang Yazdani
Keyword(s):  
Flip Chip ◽  
Thermal Stresses ◽  
Stress Test ◽  
Temperature Cycle ◽  
3D Integration ◽  
Test Vehicle ◽  
Direct Assembly ◽  
Solder Balls ◽  
Present Design ◽  
The Cost

Silicon interposer is emerging as a vehicle for integrating dies with sub 50um bump pitch in 2.5D/3D configuration. Benefits of 2.5D/3D integration are well explained in the literature, however, cost and reliability is a major concern especially with the increase in interposer size. Among the challenges, reliability issues such as warpage, cracks and thermal-stresses must be managed, in addition, multi-layer build-up flip chip substrate cost and its impact on the overall yield must be considered. Because of these challenges, 2.5D/3D silicon interposer has developed a reputation as a costly process. To overcome the reliability challenges and cost associated with typical thin interposer manufacturing and assembly, a rigid silicon interposer type structure is disclosed. In this study, interposer with thickness of greater than 300um is referred to as rigid interposer. Rigid silicon interposer is directly assembled on PCB without the need for intermediary substrate. This eliminates the need for an intermediary substrate, thin wafer handling, wafer bonding/debonding procedures and Through Silicon Via (TSV) reveal processes, thus, substantially reducing the cost of 2.5D/3D integrated products while improving reliability. A 10X10mm2 rigid silicon interposer test vehicle with 310um thickness was designed and fabricated. BGA side of the interposer with 1mm ball pitch was bumped with eutectic solder balls through a reflow process. Interposer was then assembled on a 50X50mm2 FR-4 PCB. We present design and direct assembly of the rigid silicon interposer on PCB followed by temperature cycle results using CSAM images at 250, 500, 750 and 1000 cycles. It is shown that all samples successfully passed the temperature cycle stress test.

Impact of isothermal aging on fine pitch BGA packages with Sn-Ag-Cu solder interconnects

2010 ◽  
Vol 2010 (1) ◽  
pp. 000298-000305
Author(s):  
Tae-Kyu Lee ◽  
Weidong Xie ◽  
Thomas R. Bieler ◽  
Kuo-Chuan Liu ◽  
Jie Xue
Keyword(s):  
Thermal Cycling ◽  
Microstructure Evolution ◽  
Isothermal Aging ◽  
Substrate Surface ◽  
Solder Interconnects ◽  
Surface Finishes ◽  
Bga Packages ◽  
Fine Pitch ◽  
Solder Balls

The interaction between isothermal aging and long-term reliability of fine pitch ball grid array (BGA) packages with Sn-3.0Ag-0.5Cu (wt%) solder ball interconnects are investigated. In this study, 0.4mm fine pitch packages with 0.3mm diameter Sn-Ag-Cu solder balls are used. Two different die sizes and two different package substrate surface finishes are selected to compare the internal strain impact and alloy effect, especially the Ni effect during thermal cycling. To see the thermal impact on the thermal performance and long-term reliability, the samples are isothermally aged and thermal cycled from 0 to 100°C with a 10minute dwell time. Based on weibull plots for each aging condition, the lifetime of the package reduced approximately 44% with 150°C aging precondition. The microstructure evolution is observed during thermal aging and thermal cycling with different phase microstructure transformations between electrolytic Ni/Au and OSP surface finishes, focusing on the microstructure evolution near the package side interface. Different mechanisms after aging at various conditions are observed, and their impacts on the fatigue life of solder joints are discussed.

Interaction of thermal cycling and electric current on reliability of solder joints in different solder balls

2019 ◽  
Vol 6 (10) ◽  
pp. 106302 ◽  
Author(s):  
Yufeng Jiao ◽  
Kittisak Jermsittiparsert ◽  
Aleksandr Yu Krasnopevtsev ◽  
Qahtan A Yousif ◽  
Mohammad Salmani
Keyword(s):  
Thermal Cycling ◽  
Electric Current ◽  
Solder Joints ◽  
Solder Balls ◽  
Reliability Of Solder Joints

scholarly journals A Method For Parallel, Automated, Thermal Cycling of Submicroliter Samples

2001 ◽  
Vol 11 (3) ◽  
pp. 441-447
Author(s):  
Jonathan Nakane ◽  
David Broemeling ◽  
Roger Donaldson ◽  
Andre Marziali ◽  
Thomas D. Willis ◽  
...  
Keyword(s):  
Dna Sequencing ◽  
Thermal Cycling ◽  
High Throughput ◽  
Dna Analysis ◽  
Detection Efficiency ◽  
Large Fraction ◽  
Cycle Sequencing ◽  
High Throughput Dna Sequencing ◽  
Reaction Volumes ◽  
The Cost

A large fraction of the cost of DNA sequencing and other DNA-analysis processes results from the reagent costs incurred during cycle sequencing or PCR. In particular, the high cost of the enzymes and dyes used in these processes often results in thermal cycling costs exceeding $0.50 per sample. In the case of high-throughput DNA sequencing, this is a significant and unnecessary expense. Improved detection efficiency of new sequencing instrumentation allows the reaction volumes for cycle sequencing to be scaled down to one-tenth of presently used volumes, resulting in at least a 10-fold decrease in the cost of this process. However, commercially available thermal cyclers and automated reaction setup devices have inherent design limitations which make handling volumes of <1 μL extremely difficult. In this paper, we describe a method for thermal cycling aimed at reliable, automated cycling of submicroliter reaction volumes.

Design and Reliability in Electronic Packaging Including Power Temperature Cycling and Vibration Effects

2003 ◽  
Author(s):  
Mark D. Nickerson ◽  
Chandrakant S. Desai
Keyword(s):  
Finite Element ◽  
Failure Analysis ◽  
Thermal Cycling ◽  
Temperature Cycling ◽  
Damage Models ◽  
Disturbed State Concept ◽  
Solder Balls ◽  
Element Failure ◽  
Viscoplastic Models ◽  
Cycles To Failure

Thermomechanical, power temperature cycling (PTC) and vibration analyses were performed on a 313 staggered pin PBGA package using plastic and viscoplastic disturbed-state damage models. An accelerated finite element failure analysis was performed using a newly developed procedure. Validations were performed using published PBGA test data. The disturbed state concept was used to model the disturbance (damage) accumulated in PBGA solder joints subjected to thermal cycling (PTC and TCT), vibration, and vibration coupled with three distinct temperatures. 2D FEA plastic and viscoplastic models were created based on a diagonal “slice” of the PBGA. This allowed the most critical solder balls (under the die and furthest DNP) to be analyzed in the same model. The thermal cycling results indicate that the solder balls under the die are the most likely to fail. The vibration results indicate the solder balls furthest from the package center are most likely to fail. The vibration results, coupled with distinct isothermal temperatures, indicate that as temperature increases, the cycles to failure decreases.

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