Voiding and Thermal Resistance Modeling and Characterization for a QFN Assembly

2010 ◽  
Author(s):  
Harish Gadepalli ◽  
Rangaraj Dhanasekaran ◽  
S. Manian Ramkumar ◽  
Tim Jensen ◽  
Ed Briggs
Keyword(s):  
Thermal Resistance ◽  
Void Formation ◽  
Primary Objective ◽  
Void Volume ◽  
Thermal Dissipation ◽  
Electrical Performance ◽  
Solder Paste ◽  
Resistance Response ◽  
Response Variable ◽  
The Impact

Quad Flatpack No lead (QFN) packages have become a popular choice in electronics packaging due to its small form factor. They are also gaining rapid industry acceptance because of its excellent thermal and electrical performance. The bottom side of the QFN package has a large thermal pad. This exposed die attach pad effectively conducts heat to the PCB and also provides a stable ground connection. Effective soldering of this surface to the pad on the PCB is required for good thermal dissipation and component functionality. The exposed thermal pad presents various challenges during the surface mount assembly process. One major challenge is solder void formation. Voids are primarily formed due to the entrapment of volatiles in flux outgassing during the reflow process. The primary objective of this study is to determine optimal parameters to minimize void formation in QFN packages (QFN16, QFN20, QFN28, QFN32 and QFN44), specifically the reflow profile, lead-free solder paste and stencil aperture opening for the thermal pad. A systematic Design of Experiments (DOE) based approach was used to arrive at conclusions, using the ratio of void volume on the thermal pad to the actual volume of solder paste printed, as the response variable. A theoretical thermal resistance response variable was also modeled to analyze the DOE parameters and the conclusions were similar to the void model. Various graphs are presented to understand the impact of different parameters. Interaction graphs are used to determine optimal settings for each parameter. A regression equation for relationship between the factors and the void volume is identified to predict void volumes for any given component, paste volume and paste transfer efficiency.

Characterizing and Minimizing Voids in Quad Flat No-Lead Pack (QFN) Device Assembly Using Pb-Free Solder Alloys

2009 ◽  
Author(s):  
Rangaraj Dhanasekaran ◽  
Harish Gadepalli ◽  
S. Manian Ramkumar ◽  
Tim Jensen ◽  
Ed Briggs
Keyword(s):  
Void Formation ◽  
Primary Objective ◽  
Thermal Dissipation ◽  
Electrical Performance ◽  
Solder Paste ◽  
Die Attach ◽  
Aperture Opening ◽  
Free Solder ◽  
Small Form Factor ◽  
The Impact

Quad Flatpack No lead (QFN) packages have become a popular choice in electronics packaging due to its small form factor. They are also gaining rapid industry acceptance because of its excellent thermal and electrical performance. The bottom side of the QFN package has a large thermal pad. This exposed die attach pad effectively conducts heat to the PCB and also provides a stable ground connection. Effective soldering of this surface to the pad on the PCB is required for good thermal dissipation and component functionality. The exposed thermal pad presents various challenges during the surface mount assembly process. One major challenge is solder void formation. Voids are primarily formed due to the entrapment of volatiles in flux outgassing during the reflow process. The primary objective of this study is to determine optimal parameters to minimize void formation in QFN packages (QFN16, QFN20, QFN28 and QFN32), specifically the reflow profile, lead-free solder paste and stencil aperture opening for the thermal pad. A systematic DOE based approach was used to arrive at conclusions, using the ratio of void volume on the thermal pad to the actual volume of solder paste printed as the response variable. Various graphs are presented to understand the impact of different parameters. Interaction graphs are used to determine optimal settings for each parameter.

Impact of Thermal Sub-Continuum Effects on Electrical Performance of Silicon-on-Insulator Transistors

2005 ◽  
Author(s):  
Keivan Etessam-Yazdani ◽  
Rozana Hussin ◽  
Mehdi Asheghi
Keyword(s):  
Thermal Resistance ◽  
Drain Current ◽  
Silicon On Insulator ◽  
Electrical Performance ◽  
Gate Length ◽  
Boundary Scattering ◽  
Self Heating ◽  
Soi Devices ◽  
The Impact ◽  
Channel Region

In this manuscript, the impact of scaling on self-heating of silicon-on-insulator (SOI) transistors is investigated. Effect of temperature dependent phonon-boundary scattering in silicon thin films, which results in reduction in thermal conduction in the channel region, is incorporated into a electro-thermal simulation tool. Results of DC electro-thermal simulations are used to study drain current degradation due to self-heating and to obtain the thermal resistance of SOI devices as a function of gate length and silicon layer thickness. The device thermal resistance is increased by nearly a factor of 3 due to the scaling of gate length from 180nm to 10nm. Self-heating in SOI devices with gate length of 10nm can be responsible for up to 30% reduction in the saturation current and neglecting phonon-boundary scattering in the channel region may underestimate the degradation of drain current due to self-heating by nearly a factor of two.

scholarly journals Digital Addiction: Systematic Review of Computer Game Addiction Impact on Adolescent Physical Health

Electronics ◽  
2021 ◽  
Vol 10 (9) ◽  
pp. 996
Author(s):  
Norshakirah Aziz ◽  
Md Jan Nordin ◽  
Said Jadid Abdulkadir ◽  
Muhammad Muhaimin M. Salih
Keyword(s):  
Physical Health ◽  
Computer Games ◽  
Relevant Literature ◽  
Primary Objective ◽  
Extensive Literature ◽  
Literature Study ◽  
Computer Gaming ◽  
Digital Addiction ◽  
The Impact ◽  
Malaysian Adolescents

The advancement of technology has enabled powerful microprocessors to render high-quality graphics for computer gaming. Despite being intended for leisure purposes, several components of the games alongside the gamer’s environmental factors have resulted in digital addiction (DA) towards computer games such as massively multiplayer online games (MMOG). Excessive gaming among adolescents has various negative impacts on an individual. However, only a few researchers have addressed the impact of DA on physical health. Thus, the primary objective of this research is to study the impact of DA on physical health among Malaysian adolescents. This study focuses on Malaysian adolescents of ages 12–18 years old who are addicted to computer games, specifically the MMOG. The methodology used for the study involves focus group discussions (FGD) and extensive literature study. The FGD sessions have involved both medical experts and game experts. The outcome of FGD discussion is recorded and justified with the existing relevant literature from high-impact journals, theses, conferences, books, and reports. This paper provides evidence of five physical health impacts of DA associated with adolescents. The factors of DA, the addiction components existing in MMOG computer games, and the DA health risk assessment are presented in the results section. Based on the study, it is concluded that DA among Malaysian adolescents can cause various impacts on physical health such as obesity, back pain, and neck pain, orthopaedic/joint muscle, eyesight problem, hearing problem, as well as physical inactivity.

scholarly journals Fire Resistance Behaviour of Geopolymer Concrete:An Overview

Buildings ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 82
Author(s):  
Salmabanu Luhar ◽  
Demetris Nicolaides ◽  
Ismail Luhar
Keyword(s):  
Compressive Strength ◽  
Thermal Resistance ◽  
Building Materials ◽  
Elevated Temperatures ◽  
Construction Materials ◽  
Flexural Behavior ◽  
Thermal Shrinkage ◽  
Physico Chemical ◽  
The Impact ◽  
Loss Of Strength

Even though, an innovative inorganic family of geopolymer concretes are eye-catching potential building materials, it is quite essential to comprehend the fire and thermal resistance of these structural materials at a very high temperature and also when experiencing fire with a view to make certain not only the safety and security of lives and properties but also to establish them as more sustainable edifice materials for future. The experimental and field observations of degree of cracking, spalling and loss of strength within the geopolymer concretes subsequent to exposure at elevated temperature and incidences of occurrences of disastrous fires extend an indication of their resistance against such severely catastrophic conditions. The impact of heat and fire on mechanical attributes viz., mechanical-compressive strength, flexural behavior, elastic modulus; durability—thermal shrinkage; chemical stability; the impact of thermal creep on compressive strength; and microstructure properties—XRD, FTIR, NMR, SEM as well as physico-chemical modifications of geopolymer composites subsequent to their exposures at elevated temperatures is reviewed in depth. The present scientific state-of-the-art review manuscript aimed to assess the fire and thermal resistance of geopolymer concrete along with its thermo-chemistry at a towering temperature in order to introduce this novel, most modern, user and eco-benign construction materials as potentially promising, sustainable, durable, thermal and fire-resistant building materials promoting their optimal and apposite applications for construction and infrastructure industries.

scholarly journals Application of ZnO Nanoparticles in Sn99Ag0.3 Cu0.7-Based Composite Solder Alloys

Nanomaterials ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 1545
Author(s):  
Agata Skwarek ◽  
Olivér Krammer ◽  
Tamás Hurtony ◽  
Przemysław Ptak ◽  
Krzysztof Górecki ◽  
...  
Keyword(s):  
Solder Alloy ◽  
Zno Nanoparticles ◽  
Composite Solder ◽  
Void Formation ◽  
Particle Sizes ◽  
Solder Paste ◽  
Solder Alloys ◽  
Ion Microscopy ◽  
Zno Ceramics ◽  
Thermoelectric Parameters

The properties of Sn99Ag0.3Cu0.7 (SACX0307) solder alloy reinforced with ZnO nanoparticles were investigated. The primary ZnO particle sizes were 50, 100, and 200 nm. They were added to a solder paste at a ratio of 1.0 wt %. The wettability, the void formation, the mechanical strength, and the thermoelectric parameters of the composite solder alloys/joints were investigated. Furthermore, microstructural evaluations were performed using scanning electron and ion microscopy. ZnO nanoparticles decreased the composite solder alloys’ wettability, which yielded increased void formation. Nonetheless, the shear strength and the thermoelectric parameters of the composite solder alloy were the same as those of the SACX0307 reference. This could be explained by the refinement effects of ZnO ceramics both on the Sn grains and on the Ag3Sn and Cu6Sn5 intermetallic grains. This could compensate for the adverse impact of lower wettability. After improving the wettability, using more active fluxes, ZnO composite solder alloys are promising for high-power applications.

Quantitative Evaluation of Voids in Lead Free Solder Joints

2015 ◽  
Vol 772 ◽  
pp. 284-289 ◽  
Author(s):  
Sabuj Mallik ◽  
Jude Njoku ◽  
Gabriel Takyi
Keyword(s):  
Solder Bump ◽  
Solder Joints ◽  
Void Formation ◽  
Lead Free ◽  
Lead Free Solder ◽  
Solder Paste ◽  
X Ray ◽  
Size And Shape ◽  
Solder Bumps ◽  
Free Solder

Voiding in solder joints poses a serious reliability concern for electronic products. The aim of this research was to quantify the void formation in lead-free solder joints through X-ray inspections. Experiments were designed to investigate how void formation is affected by solder bump size and shape, differences in reflow time and temperature, and differences in solder paste formulation. Four different lead-free solder paste samples were used to produce solder bumps on a number of test boards, using surface mount reflow soldering process. Using an advanced X-ray inspection system void percentages were measured for three different size and shape solder bumps. Results indicate that the voiding in solder joint is strongly influenced by solder bump size and shape, with voids found to have increased when bump size decreased. A longer soaking period during reflow stage has negatively affectedsolder voids. Voiding was also accelerated with smaller solder particles in solder paste.

Abstract P301: Evaluating the Impact of a Pharmacist-Managed Hypertension Collaborative Care Model in Vascular Neurology Patients in an Inpatient Acute Care Setting

Stroke ◽  
2021 ◽  
Vol 52 (Suppl_1) ◽  
Author(s):  
Ann Smith ◽  
Kathleen Bledsoe ◽  
Thomas Madden ◽  
Jamie Artale ◽  
Ted Sindlinger
Keyword(s):  
Blood Pressure ◽  
Acute Care ◽  
Care Setting ◽  
Management Practice ◽  
Primary Objective ◽  
Adverse Outcomes ◽  
Acute Care Setting ◽  
Percentage Reduction ◽  
Improvement Project ◽  
The Impact

Introduction: The utility of pharmacist-managed collaborative practice agreements (CPA) in the management of hypertension is well established in the outpatient setting. There has been little evaluation of the use of CPAs in the inpatient acute care setting, and none described specifically in the vascular neurology population. Treatment of hypertension is a critical intervention for the secondary prevention of acute ischemic stroke. This quality improvement project evaluated the implementation of a CPA for the inpatient acute care management of hypertension in vascular neurology patients at University of Virginia Health. Methods: A CPA was developed between the neurosciences clinical pharmacist group and the inpatient vascular neurology service, legally vetted, and implemented in June 2019. All vascular neurology patient charts in which an electronic CPA referral was placed from June 2019 through June 2020 were reviewed. Patients were excluded if they were discharged within 24 hours of the referral being placed. The primary objective was to describe and evaluate the implementation of a pharmacist-driven hypertension management practice in the inpatient acute care setting. All patient demographic and clinical data were analyzed using descriptive statistics. Secondary safety outcomes included documented hypotensive events (SBP <90) and acute kidney injury (AKI, increase in SCr by 0.3 mg/dl within 48 hours). Results: During the study period, 26 referrals were placed, and 19 patients were included for review. On average, patients were on 2 anti-hypertensive medications prior to admission. From the time of referral to discharge (mean 6 days), systolic blood pressure (SBP) was reduced on average by 36 mmHg (mean percentage reduction 20%) and diastolic blood pressure (DBP) by 12 mmHg (mean percentage reduction 7%). Ten patients (53%) met the goal of SBP < 140 at discharge. There were 5 hypotensive events and 4 instances of AKI, all of which were mild and recovered prior to discharge. Conclusion: A pharmacist-managed hypertension CPA was successfully implemented in vascular neurology patients in the inpatient acute care setting. The practice demonstrated improved blood pressure control and minimal adverse outcomes.

Sensitivity of the neutron multiplication factor to water ingress into a spent fuel cask

Kerntechnik ◽  
2020 ◽  
Vol 85 (1) ◽  
pp. 38-53
Author(s):  
M. J. Leotlela ◽  
I. Petr ◽  
A. Mathye
Keyword(s):  
Gradual Increase ◽  
Primary Objective ◽  
Fuel Pellet ◽  
Main Body ◽  
Spent Fuel ◽  
Reactivity Effect ◽  
Water Ingress ◽  
Accident Scenarios ◽  
The Impact ◽  
Gain Access

Abstract An essential component of safety analyses is the investigation of accident scenarios. In this paper water ingress scenarios of spent fuel containers, as they may occur during transport or storage, are examined. In the main body of this paper, a number of paths are studied through which water can gain access to the spent fuel cask and eventually reach the fuel pellet, potentially resulting in an increase in reactivity as a result of over-moderation. The primary objective of this project was to perform an assessment of what, in the unlikely event of a Fukushima- type accident, the impact would be on the reactivity of the cask by analyzing a gradual increase in water level in the spent fuel casks. In addition, the way the keff of the system responds to such an increase is discussed. The paper also provides the results of an assessment of the reactivity effect of water ingress via various pathways/channels.

Quality of Life of Family Caregivers of Patients With Cancer in Korçe, Albania

2018 ◽  
Vol 34 (2) ◽  
pp. 118-125 ◽  
Author(s):  
Jonathon Judkins ◽  
Irena Laska ◽  
Judith Paice ◽  
Priya Kumthekar
Keyword(s):  
Quality Of Life ◽  
Well Being ◽  
Risk Groups ◽  
The United States ◽  
Primary Objective ◽  
Care Clinic ◽  
Demographic Groups ◽  
Spiritual Well Being ◽  
The Impact

Purpose: The primary objective of this study was to quantify cancer family caregiver (FCG) quality of life (QOL) in a Southern Albanian population and to determine whether differences exist between 4 domains of QOL (physical, psychological, social, and spiritual). This study also sought to compare QOL in our cohort to QOL in historical studies that used the same survey instrument, and to examine correlations between demographic characteristics and QOL to identify any high-risk groups. Methods: A sample of 40 FCGs was recruited at the Mary Potter Palliative Care Clinic in Korçe, Albania. Each participant completed the City of Hope Quality of Life (Family Version), a validated 37-question instrument that measures caregiver well-being in 4 domains: physical, psychological, social, and spiritual well-being. Results: There were no significant differences between the composite scores of the 4 QOL domains in our study. However, there were differences when comparing self-reported QOL between domains (“Rate your overall physical/psychological/social/spiritual well-being”). The QOL measured in our study was significantly lower than in 3 studies from the United States that used the same questionnaire. There were no significant correlations between demographic groups and QOL. Conclusions: This study examines the impact that the paucity of palliative services has on the QOL of Albanian cancer FCGs. Although there were no domains of QOL or demographic groups identified in our study that were faring significantly worse than others, the poor overall QOL provides further evidence to support the continued development of palliative services for both patients and family members in Albania.

scholarly journals Evaluating the impact of type 2 diabetes mellitus on CYP450 metabolic activities: protocol for a case–control pharmacokinetic study

BMJ Open ◽  
2018 ◽  
Vol 8 (2) ◽  
pp. e020922 ◽  
Author(s):  
Sophie Gravel ◽  
Jean-Louis Chiasson ◽  
Suzanne Dallaire ◽  
Jacques Turgeon ◽  
Veronique Michaud
Keyword(s):  
Diabetes Mellitus ◽  
Type 2 Diabetes ◽  
Type 2 Diabetes Mellitus ◽  
Adult Population ◽  
Study Groups ◽  
Primary Objective ◽  
Research Centre ◽  
Probe Drug ◽  
The Impact

IntroductionDiabetes affects more than 9% of the adult population worldwide. Patients with type 2 diabetes mellitus (T2DM) show variable responses to some drugs which may be due, in part, to variability in the functional activity of drug-metabolising enzymes including cytochromes P450 (CYP450s). CYP450 is a superfamily of enzymes responsible for xenobiotic metabolism. Knowledge must be gained on the impact of T2DM and related inflammatory processes on drug metabolism and its consequences on drug response. The aim of this study is to characterise the activity of CYP1A2, CYP2B6, CYP2C9, CYP2C19, CYP2D6, CYP2E1 and CYP3A4/5 in T2DM versus non-T2DM subjects following the administration of a cocktail of probe drug substrates.Methods and analysisThis single-centre clinical study proposes the first detailed characterisation of T2DM impacts on major CYP450 drug-metabolising enzyme activities. We intend to recruit 42 patients with controlled T2DM (A1C≤7%), 42 patients with uncontrolled T2DM (A1C>7%) and 42 non-diabetic control subjects. The primary objective is to determine and compare major CYP450 activities in patients with T2DM versus non-diabetic subjects by dosing in plasma and urine probe drug substrates and metabolites following the oral administration of a drug cocktail: caffeine (CYP1A2), bupropion (CYP2B6), tolbutamide (CYP2C9), omeprazole (CYP2C19), dextromethorphan (CYP2D6), chlorzoxazone (CYP2E1) and midazolam (CYP3A4/5). Secondary objectives will evaluate the influence of variables such as glycaemia, insulinaemia, genetic polymorphisms and inflammation. The value of an endogenous biomarker of CYP3A activity is also evaluated. The first patient was recruited in May 2015 and patients will be enrolled up to completion of study groups.Ethics and disseminationApproval was obtained from the ethic review board of the CHUM research centre (Montreal, Canada).Trial registration numberNCT02291666.

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