Effect of Design Factors on Microvia Reliability of Flip Chip Ball Grid Array Polymeric Substrates

2008 ◽  
Vol 5 (3) ◽  
pp. 104-115
Author(s):  
Dennis Leung ◽  
Guna Selvaduray
Keyword(s):  
Electrical Resistance ◽  
High Performance ◽  
Flip Chip ◽  
Ball Grid Array ◽  
Temperature Cycling ◽  
Low Aspect Ratio ◽  
Cte Mismatch ◽  
Polymeric Substrates ◽  
Design Factors ◽  
The Relationship

Microvia failures in flip chip ball grid array (FCBGA) polymeric substrates have been a major concern in the development of reliable packages for high-performance and high-density chips. To determine the relationship between reliability and design factors of the microvias, a 10-layer substrate was used to investigate these contrasting design factors: “stack-on-core” vs. “non–stack-on-core,” “high” vs. “low” aspect ratio, “stacked” vs. “staggered,” and “fillet” vs. “non-fillet.” Temperature cycling was used to generate stresses on the microvias. Electrical resistance was measured and analyzed, using design of experiment (DOE), to determine the effects of these design factors on microvia reliability. The significant single factors for a robust microvia were “non–stack-on-core” and “staggered.” Cross-sectioning was employed to understand the failure pattern. Cracks occurred on “stack-on-core” and “stacked” designs only. All the cracks were located at the interface between the capture pad and the bottom of the microvia, where stress is the highest due to the CTE mismatch of different materials.

Interface Adhesion and Reliability of Microsystem Packaging

2003 ◽  
Vol 782 ◽  
Author(s):  
Marvin I. Francis ◽  
Kellen Wadach ◽  
Satyajit Walwadkar ◽  
Junghyun Cho
Keyword(s):  
High Performance ◽  
Flip Chip ◽  
Coefficient Of Thermal Expansion ◽  
Dissimilar Materials ◽  
Strain Energy Release ◽  
Interface Adhesion ◽  
Curing Conditions ◽  
Chip Technology ◽  
Solder Balls ◽  
Cte Mismatch

ABSTRACTFlip-chip technology is becoming one of the most promising packaging techniques for high performance packages. Solder balls are used as the connection technique in the flip-chip method and the connections are reinforced by filling in the spacing between the chip and substrate with underfill. The function of the underfill is to reduce the stresses in the solder joints caused by a coefficient of thermal expansion (CTE) mismatch. The presence of polymeric underfill material will, however, make the flip-chip packaging system susceptible to interfacial failure. Thus, the purpose of this study is to examine the interfacial delamination between the dissimilar materials in order to increase the reliability of the flip-chip interconnection method, and to understand the effect of underfill curing conditions on the interface adhesion. In particular, we use a linear elastic fracture mechanics (LEFM) approach to assess interfacial toughness. For this purpose, four-point bending testing is performed to determine a critical strain energy release rate, Gc. In addition, nano-indentation testing equipped with atomic force microscope (AFM) is employed to determine structure and properties of the underfill layer.

Effect of Package and Board Pad Size on Optimum Flip Chip Ball Grid Array (FCBGA) Package Thermo-Mechanical Performance

2003 ◽  
Author(s):  
Chee Wai Wong ◽  
Cheng Siew Tay ◽  
Siew Sang Tan ◽  
Vasu Vasudevan ◽  
Eng Huat Goh ◽  
...  
Keyword(s):  
Solder Joint ◽  
Flip Chip ◽  
Mechanical Performance ◽  
Ball Grid Array ◽  
Temperature Cycling ◽  
Dominant Factor ◽  
Process Window ◽  
Key Factors ◽  
Optimum Range ◽  
Free Zone

Flip Chip Ball Grid Array (FCBGA) has been a common package technology to achieve higher Input/Output (IO) count. In moving toward higher IO count without increasing the package size, FCBGA package with tighter pitch is required. Unfortunately, ball pitch reduction from 1.27mm to 1mm in FCBGA packages is not a transparent change. Instead, it provides an inside into the thermo-mechanical performance of FCBGA solder joint. Previous study indicated the importance of the package solder resist opening-to-board pad size ratio (AR) as the dominant factor in improving the thermo-mechanical performance of the solder joint at one solder system. An optimum range of AR had been defined as failure free zone with respect to the temperature cycling stress from −40degC to 85degC. This paper is a continued study, which focused on identifying the optimum range of AR for failure free zone. Key factors under the study are package solder resist opening (SRO), die size, population pattern, type of board pad, type of package design and thermal solution. This paper consolidates the modeling and empirical data on the relationship. The results of the study has brought towards an identification of process window for 1mm pitch FCBGA package and led to package and board design rules in terms of targeted SRO & board pad size, type of pad design and a tightening of SRO & board pad size specification. Besides, the learning has led towards a new look into the BGA package certification in which SRO and board pad size are key factors in the design consideration.

Stresses in Area Array Assemblies Subjected to Thermal Cycling

2009 ◽  
Author(s):  
Jordan Roberts ◽  
M. Kaysar Rahim ◽  
Safina Hussain ◽  
Jeffrey C. Suhling ◽  
Richard C. Jaeger ◽  
...  
Keyword(s):  
Finite Element ◽  
Thermal Cycling ◽  
Flip Chip ◽  
Ball Grid Array ◽  
Temperature Cycling ◽  
Aging Effects ◽  
Area Array ◽  
Die Surface ◽  
Test Chips

Thermal cycling accelerated life testing is often used to qualify area array packages (e.g. Ball Grid Arrays and Flip Chip) for various applications. Finite element life predictions for thermal cycling configurations are challenging due to the complicated temperature/time dependent constitutive relations and failure criteria needed for solders and encapsulants and their interfaces, aging/evolving material behavior (e.g. solders), difficulties in modeling plating finishes, the complicated geometries of typical electronic assemblies, etc. In addition, in-situ measurements of stresses and strains in assemblies subjected to temperature cycling is difficult because of the extreme environmental conditions and the fact that the primary materials/interfaces of interest (e.g. solder joints, die device surface, wire bonds, etc.) are embedded within the assembly (not at the surface). For these reasons, we really know quite little about the evolution of the stresses, strains, and deformations occurring within sophisticated electronic packaging geometries during thermal cycling. In our research, we are using test chips containing piezoresistive stress sensors to continuously characterize the in-situ die surface stress during long-term thermal cycling of several different area array packaging technologies including plastic ball grid array (PBGA) components, ceramic ball grid array (CBGA) components, and flip chip on laminate assemblies. The utilized (111) silicon test chips are able to measure the complete three-dimensional stress state (all 6 stress components) at each sensor site being monitored by the data acquisition hardware. The die stresses are initially measured at room temperature after packaging. The assemblies are then subjected to thermal cycling over various temperature ranges including 0 to 100 °C, −40 to 125 °C, and −55 to 125 °C, for up to 3000 thermal cycles. During the thermal cycling, sensor resistances at critical locations on the die device surface (e.g. the die center and die corners) are recorded. From the resistance data, the stresses at each site can be calculated and plotted versus time. The experimental observations show significant cycle-to-cycle evolution in the stress magnitudes due to material aging effects, stress relaxation and creep phenomena, and development of interfacial damage. The observed stress variations as a function of thermal cycling duration are also being correlated with the observed delaminations at the die surface (as measured using scanning acoustic microscopy (C-SAM)) and finite element simulations that include material constitutive models that incorporate thermal aging effects.

Corrosion Problems in a Refinery Diethanolamine System

CORROSION ◽  
1960 ◽  
Vol 16 (10) ◽  
pp. 503t-506t ◽  
Author(s):  
KENNETH L. MOORE
Keyword(s):  
Hydrogen Sulfide ◽  
Electrical Resistance ◽  
System Operation ◽  
Measuring Device ◽  
Acid Gas ◽  
Gas Streams ◽  
The Rich ◽  
The Relationship ◽  
Refinery Gas ◽  
Propane Butane

Abstract Various corrosion problems are described which have occurred in a large diethanolamine (DEA) system that removes hydrogen sulfide from refinery gas streams and a liquid propane-butane stream. These include reboiler corrosion, rich DEA corrosion, stress corrosion cracking, and corrosion-erosion. The effect of the problems on system operation is discussed, as well as the means of minimizing the problems. Electrical resistance measuring device data indicate the importance of keeping the solution loading below 0.34 mol of acid gas (H2S + CO2) per mol of DEA to minimize the corrosion in the rich DEA. Data from this source also show the relationship between general reboiler corrosion and solution contamination. 8.4.3

scholarly journals The Relationship between Learning Styles and Academic Performance: Consistency among Multiple Assessment Methods in Psychology and Education Students

2021 ◽  
Vol 13 (6) ◽  
pp. 3341
Author(s):  
Jesús Maya ◽  
Juan F. Luesia ◽  
Javier Pérez-Padilla
Keyword(s):  
Early Childhood ◽  
Academic Performance ◽  
Learning Styles ◽  
Primary Education ◽  
High Performance ◽  
Multiple Choice ◽  
Assessment Methods ◽  
Theory And Practice ◽  
Education Students ◽  
The Relationship

Universities strive to ensure quality education focused on the diversity of the student body. According to experiential learning theory, students display different learning preferences. This study has a three-fold objective: to compare learning styles based on personal and educational variables, to analyze the association between learning styles, the level of academic performance, and consistency of performance in four assessment methods, and to examine the influence of learning dimensions in students with medium-high performance in the assessment methods. An interdisciplinary approach was designed involving 289 psychology, early childhood education and primary education students at two universities in Spain. The Learning Style Inventory was used to assess learning styles and dimensions. The assessment methods used in the developmental psychology course included the following question formats: multiple-choice, short answer, creation-elaboration and an elaboration question on the relationship between theory and practice. Univariate analysis, multivariate analysis, and binomial logistic models were computed. The results reveal Psychology students to be more assimilative (theoretical and abstract), while early childhood and primary education students were evenly distributed among styles and were more divergent and convergent (practical) in absolute terms. In addition, high scores in perception (abstract conceptualization) were associated with a high level of performance on the multiple-choice tests and the elaboration question on the relationship between theory and practice. Abstract conceptualization was also associated with medium-high performance in all assessment methods and this variable predicted consistent high performance, independent of the assessment method. This study highlights the importance of promoting abstract conceptualization. Recommendations for enhancing this learning dimension are presented.

scholarly journals Relationship between Plasma Trimethylamine N-Oxide Levels and Renal Dysfunction in Patients with Hypertension

2021 ◽  
pp. 1-12
Author(s):  
Jia Zhou ◽  
Dingkun Wang ◽  
Bingong Li ◽  
Xuelian Li ◽  
Xingjun Lai ◽  
...  
Keyword(s):  
Blood Pressure ◽  
Kidney Disease ◽  
Renal Dysfunction ◽  
High Performance ◽  
Characteristic Curve ◽  
Area Under The Curve ◽  
Hypertensive Patients ◽  
Ckd Stage ◽  
Liquid Chromatography Tandem Mass ◽  
The Relationship

<b><i>Introduction:</i></b> Trimethylamine N-oxide (TMAO) is a metabolite produced by gut bacteria. Although increased TMAO levels have been linked to hypertension (HTN) and chronic kidney disease (CKD) with poor prognosis, no clinical studies have directly addressed the relationship between them. In this study, we investigated the relationship between TMAO and renal dysfunction in hypertensive patients. <b><i>Methods:</i></b> We included healthy controls (<i>n</i> = 50), hypertensive patients (<i>n</i> = 46), and hypertensive patients with renal dysfunction (<i>n</i> = 143). Their blood pressure values were taken as the highest measured blood pressure. Renal function was evaluated using the estimated glomerular filtration rate. Plasma TMAO levels were measured using high-performance liquid chromatography tandem mass spectrometry. <b><i>Results:</i></b> We found significant differences in plasma TMAO levels among the 3 groups (<i>p</i> &#x3c; 0.01). The plasma TMAO of patients with HTN was significantly higher than that of healthy people, and the plasma TMAO of patients with HTN complicated by renal dysfunction was significantly higher than either of the other groups. Patients in the highest TMAO quartile were at a higher risk of developing CKD stage 5 than those in the lowest quartile. In the receiver operating characteristic curve, the area under the curve of TMAO combined with β 2-macroglobulin for predicting renal dysfunction in patients with HTN was 0.85 (95% confidence interval 0.80–0.90). <b><i>Conclusion:</i></b> An elevated TMAO level reflects higher levels of HTN and more severe renal dysfunction. TMAO, combined with β 2-macroglobulin levels, may assist in diagnosing CKD in hypertensive patients. Plasma TMAO has predictive value for early kidney disease in hypertensive patients.

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