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Estudo experimental da migração eletroquímica em soldagem eletrônica Sn/Ag/Cu "Lead Free".; Experimental study of eletrochemical migration of electronic soldering Sn/Ag/Cu "lead free".

Mendes, Luiz Tadeu Freire
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 10/06/2009 PT
Relevância na Pesquisa
67.02682%
Sabemos que em placas de circuito impresso montadas com tecnologia SMD Surface Mount Device podem ocorrer problemas com a migração eletroquímica. O fenômeno aparece principalmente porque os novos encapsulamentos possuem terminais com espaçamentos muito próximos. A migração eletroquímica pode tornar-se um potencial problema no processo de soldagem eletrônica quando é utilizado a tecnologia Lead Free na montagem das placas. O processo de migração eletroquímica ocorre quando temos metal, isolante e metal, em ambiente de alta umidade e sobre polarização elétrica, o metal deixa a posição inicial em forma de íon e se redeposita sobre o isolante. Em uma placa de circuito impresso, dois terminais adjacentes podem tornar-se eletrodos, dessa forma as dendritas crescem do cátodo para o ânodo. Podem aparecer diferentes morfologias com diferentes elementos envolvidos no processo de migração, dependendo da composição da pasta de solda ou acabamento da placa de circuito impresso. Uma estrutura do tipo pente comb feita sobre laminado FR4 foi utilizada nos experimentos. A distância entre as trilhas foram de 102 e 254 mícrons para simular uma distancia real dos terminais dos dispositivos. Os fatores considerados durante os experimentos foram: A distancia entre os terminais na estrutura (102 ou 254 mícrons)...

Estudo da aplicação do processo Pin-in-Paste na montagem de placas de circuito impresso usando pasta de solda lead-free (SAC).; Study of the Pin-in-Paste process in the printed circuit board assembly using lead free solder paste (SAC).

Lima, Ricardo Barbosa de
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 31/10/2011 PT
Relevância na Pesquisa
67.145464%
Neste trabalho foram estudadas as etapas de processo envolvidas na tecnologia Pin-in-Paste (PIP) de soldagem por refusão de componentes convencionais (THCs - Through Hole Components ou Componentes de Furo Passante) em placas de circuito impresso (PCIs), utilizando pasta de solda sem chumbo (lead-free) com liga SAC (Sn-Ag-Cu) de forma a atender as novas exigências ambientais para a montagem eletrônica. Inicialmente foi feito o projeto da PCI de teste com três diferentes componentes THCs e três componentes SMD com encapsulamentos distintos, com o objetivo de reproduzir uma PCI comercial. Foram gerados dois diâmetros de furos diferentes para inserir os THCs, possibilitando o estudo da variação de preenchimento com solda no PTH. Foi proposta uma equação para o cálculo do volume de pasta de solda a ser impresso sobre os furos no processo de montagem. A partir desta equação foram calculadas as dimensões dos furos do estêncil para a PCI de teste. Os parâmetros de impressão foram otimizados em função da variação de pressão e da velocidade do rodo. Duas curvas de refusão foram utilizadas, uma convencional e outra otimizada para verificar a variação na geração de defeitos. A impressão de pasta de solda ficou superior ao projetado...

Morphotropic phase boundary and electrical properties of 1-x[Bi 0.5Na0.5]TiO3 -xBa[Zr0.25Ti 0.75]O3 lead-free piezoelectric ceramics

Parija, B.; Badapanda, T.; Rout, S. K.; Cavalcante, L. S.; Panigrahi, S.; Longo, Elson; Batista, N. C.; Sinha, T. P.
Fonte: Universidade Estadual Paulista Publicador: Universidade Estadual Paulista
Tipo: Artigo de Revista Científica Formato: 4877-4886
ENG
Relevância na Pesquisa
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Lead-free solid solutions (1-x)Bi0.5Na0.5TiO 3 (BNT)-xBaZr0.25Ti0.75O3 (BZT) (x=0, 0.01, 0.03, 0.05, and 0.07) were prepared by the solid state reaction method. X-ray diffraction (XRD) and Rietveld refinement analyses of 1-x(BNT)-x(BZT) solid solution ceramic were employed to study the structure of these systems. A morphotropic phase boundary (MPB) between rhombohedral and cubic structures occured at the composition x=0.05. Raman spectroscopy exhibited a splitting of the (TO3) mode at x=0.05 and confirmed the presence of MPB region. Scanning electron microcopy (SEM) images showed a change in the grain shape with the increase of BZT into the BNT matrix lattice. The temperature dependent dielectric study showed a gradual increase in dielectric constant up to x=0.05 and then decrease with further increase in BZT content. Maximum coercive field, remanent polarization and high piezoelectric constant were observed at x=0.05. Both the structural and electrical properties show that the solid solution has an MPB around x=0.05. © 2012 Elsevier Ltd and Techna Group S.r.l.

Solidificação de ligas euteticas livres de Pb para soldagem : parametros termicos e microestrutura; Solidification of lead free eutectic solder alloys : thermal parameters and microstructure

Antonio Carlos Pires Dias
Fonte: Biblioteca Digital da Unicamp Publicador: Biblioteca Digital da Unicamp
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 28/07/2009 PT
Relevância na Pesquisa
56.81198%
As ligas de solda à base de estanho apresentam excelente fluidez e temperaturas de trabalho ideais para a união de componentes eletrônicos. A solda com ligas do sistema estanho chumbo é a mais comum para soldas em eletrônica. Entretanto, há muitas preocupações com o uso do chumbo, devido aos diversos efeitos adversos na saúde humana e contaminação do meio ambiente. Por essas razões, na maioria dos países o chumbo já é condenado e proibido de ser incorporado em diversos produtos. Neste sentido, a indústria eletrônica está de olho em soldas livres de chumbo que possam substituir a clássica solda estanho-chumbo. É objetivo deste trabalho analisar a solidificação de ligas eutéticas dos sistemas Sn-Ag e Sn-Cu, que são duas ligas com potencial de substituição. Foram desenvolvidos experimentos para determinar a influência do acabamento superficial da chapa molde nos parâmetros térmicos de solidificação durante a solidificação direcional ascendente em regime transitório de extração de calor de ligas eutéticas Sn-Pb, Sn-Cu e Sn-Ag. Foram utilizados dois tipos de acabamentos superficiais na chapa molde: lixado e ranhurado, para investigar as condições de afinidade metal/substrato. Foi desenvolvida uma abordagem teórico-experimental para determinar quantitativamente as variáveis térmicas...

Study of the interface reactions between two lead-free solders and copper substrates

Soares, Delfim; Vilarinho, Cândida; Barbosa, J.; Silva, Rosa; Castro, F.
Fonte: Universidade do Minho Publicador: Universidade do Minho
Tipo: Conferência ou Objeto de Conferência
Publicado em /05/2004 ENG
Relevância na Pesquisa
66.868223%
Traditional Sn-Pb solder alloys are being replaced, because of environmental and health concerns about lead toxicity. Among some alternative alloy systems, the Sn-Zn and Sn- Cu base alloy systems have been studied and reveal promising properties. The reliability of a solder joint is affected by the solder/substrate interaction and type of layers formed at the interface. The solder/substrate reactions, for Sn-Zn and Sn-Cu base solder alloys, were evaluated in what concerns the morphology and chemical composition of the interface layer. The phases formed at the interface between the Cu substrate and a molten lead-free solder were studied, at 250 ºC, with different stage times and alloy compositions. The melting temperatures of the studied alloys, were determined by Differential Scanning Calorimetry (DSC). Identification of equilibrium phases, formed at the interface layer, and the evaluation of their chemical compositions were performed by Scanning Electron Microscopy (SEM/EDS). Results of the studied systems were compared with the interface characteristics obtained for a traditional Sn-Pb solder alloy. Different interface characteristics were obtained, namely for the alloys containing Zn.

Effect of trace elements on the interface reactions between two lead-free solders and copper or nickel substrates

Soares, Delfim; Vilarinho, Cândida; Barbosa, J.; Samuel, Filipe; Trigo, Luisa; Bré, Paulo
Fonte: Technical Faculty Bor, Serbia Publicador: Technical Faculty Bor, Serbia
Tipo: Artigo de Revista Científica
Publicado em //2007 ENG
Relevância na Pesquisa
66.868223%
Traditional Sn-Pb solder alloys are being replaced, because of environmental and health concerns about lead toxicity. Among some alternative alloy systems, the Sn-Zn and Sn-Cu base alloy systems have been studied and reveal promising properties. The reliability of a solder joint is affected by the solder/substrate interaction and the nature of the layers formed at the interface. The solder/substrate reactions, for Sn-Zn and Sn-Cu base solder alloys, were evaluated in what concerns the morphology and chemical composition of the interface layers. The effect of the addition of P, at low levels, on the chemical composition of the layers present at the interface was studied. The phases formed at the interface between the Cu or Ni substrate and a molten lead-free solder at 250º C, were studied for different stage times and alloy compositions. The melting temperatures, of the studied alloys, were determined by Differential Scanning Calorimetry (DSC). Identification of equilibrium phases formed at the interface layer, and the evaluation of their chemical composition were performed by Scanning Electron Microscopy (SEM/EDS). Different interface characteristics were obtained, namely for the alloys containing Zn. The obtained IML layer thickness was compared...

Electromechanical properties of textured K0.5Na0.5NbO3 ceramics; Propriedades electromecânicas de cerâmicos de K0.5Na0.5NbO3 texturizado

Pinho, Rui Manuel de Oliveira
Fonte: Universidade de Aveiro Publicador: Universidade de Aveiro
Tipo: Dissertação de Mestrado
ENG
Relevância na Pesquisa
47.066646%
This work is about lead-free ceramic materials intended for electromechanical applications and candidates to replace lead-based electroceramics. One of the most widely used piezoelectric ceramics is lead zirconate titanate (PZT). However, it contains more than 60% of lead and it is toxic for humans and environment. In 2003, a directive from European Union has prohibited the use of potentially hazardous elements as lead. Due to the lack of competitive materials for PZT replacement an exception was created until a competitive alternative be found. Potassium and sodium niobate due to its high Curie temperature and moderate piezoelectric properties is currently one of the most promising lead-free materials for PZT substitution. However, its effective industrial adoption requires, among others, optimization of its properties. In this context, in this work we initially studied the effect of dopants, texturing and sintering temperature of KNN ceramics. For this purpose KNN ceramics doped with i) 1.5 mol% CuO + 2.0 mol% Li2O, ii) 1.5 mol% CuO + 4.0 mol% Li2O and iii) 1.5 mol% CuO + 0.5 mol% MnO using different sintering temperatures (1050, 1065 and 1080 °C) were prepared. In addition in order to maximize the preferential crystallographic orientation of the ceramic KNN (texturing)...

A comparison on the emission of polycyclic aromatic hydrocarbons and their corresponding carcinogenic potencies from a vehicle engine using leaded and lead-free gasoline.

Mi, H H; Lee, W J; Tsai, P J; Chen, C B
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em /12/2001 EN
Relevância na Pesquisa
46.98275%
Our objective in this study was to assess the effect of using two kinds of lead-free gasoline [including 92-lead-free gasoline (92-LFG) and 95-lead-free gasoline (95-LFG), rated according to their octane levels] to replace the use of premium leaded gasoline (PLG) on the emissions of polycyclic aromatic hydrocarbons (PAHs) and their corresponding benzo[a]pyrene equivalent (BaP(eq)) amounts from the gasoline-powered engine. The results show that the three gasoline fuels originally contained similar total PAHs and total BaP(eq) contents; however, we found significant differences in the engine exhausts in both contents. The above results suggest that PAHs originally contained in the gasoline fuel did not affect the PAH emissions in the engine exhausts. The emission factors of both total PAHs and total BaP(eq) obtained from the three gasoline fuels shared the same trend: 95-LFG > PLG > 92-LFG. The above result suggests that when PLG was replaced by 95-LFG, the emissions would increase in both total PAHs and total BaP(eq), but when replaced by 92-LFG would lead to the decreased emissions of both contents. By taking emission factors and their corresponding annual gasoline consumption rates into account, we found that both total PAH and total BaP(eq) emissions increased from 1994 to 1999. However...

Lead-free KNLNT Piezoelectric Ceramics for High-frequency Ultrasonic Transducer Application

Wu, D. W.; Chen, R. M.; Zhou, Q. F.; Shung, K. K.; Lin, D.M.; Chan, H. L. W.
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
EN
Relevância na Pesquisa
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This paper presents the latest development of a lead-free piezoelectric ceramic and its application to transducers suitable for high-frequency ultrasonic imaging. A lead-free piezoelectric ceramic with formula of (K0.5Na0.5)0.97Li0.03(Nb0.9 Ta0.1)O3 (abbreviated as KNLNT-0.03/0.10) was fabricated and characterized. The material was found to have a clamped dielectric constant ε33S = ε0 = 890, piezoelectric coefficient d33 = 245 pC/N, electromechanical coupling factor kt = 0.42 and Curie temperature Tc > 300 °C. High-frequency (40 MHz) ultrasound transducers were successfully fabricated with the lead-free material. A representative lead-free transducer had a bandwidth of 45%, two-way insertion loss of −18 dB. This performance is comparable to reported performances of popular lead-based transducers. The comparison results suggest that the lead-free piezoelectric material may serve as an alternative to lead-based piezoelectric materials for high-frequency ultrasonic transducer applications.

Characterization of Hard Piezoelectric Lead-Free Ceramics

Zhang, Shujun; Lim, Jong Bong; Lee, Hyeong Jae; Shrout, Thomas R.
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em /08/2009 EN
Relevância na Pesquisa
47.062554%
K4CuNb8O23 doped K0.45Na0.55NbO3 (KNN-KCN) ferroelectric ceramics were found to exhibit asymmetrical polarization hysteresis loops, related to the development of an internal bias field. The internal bias field is believed to be the result of defect dipoles of acceptor ions and oxygen vacancies, which lead to piezoelectric “hardening” effect, by stabilizing and pinning of the domain wall motion. The dielectric loss for the hard lead-free piezoelectric ceramic was found to be 0.6%, with mechanical quality factors Q on the order of >1500. Furthermore, the piezoelectric properties were found to decrease and the coercive field increased, when compared with the undoped material, exhibiting a typical characteristic of “hard” behavior. The temperature usage range was limited by the polymorphic phase transition temperature, being 188°C. The full set of material constants was determined for the KNN-KCN materials. Compared with conventional hard PZT ceramics, the lead-free possessed lower dielectric and piezoelectric properties; however, comparable values of mechanical Q, dielectric loss, and coercive fields were obtained, making acceptor modified KNN based lead-free piezoelectric material promising for high-power applications, where lead-free materials are desirable.

Advances in Lead-Free Piezoelectric Materials for Sensors and Actuators

Aksel, Elena; Jones, Jacob L.
Fonte: Molecular Diversity Preservation International (MDPI) Publicador: Molecular Diversity Preservation International (MDPI)
Tipo: Artigo de Revista Científica
Publicado em 10/03/2010 EN
Relevância na Pesquisa
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Piezoelectrics have widespread use in today’s sensor and actuator technologies. However, most commercially available piezoelectric materials, e.g., Pb [ZrxTi1−x] O3 (PZT), are comprised of more than 60 weight percent lead (Pb). Due to its harmful effects, there is a strong impetus to identify new lead-free replacement materials with comparable properties to those of PZT. This review highlights recent developments in several lead-free piezoelectric materials including BaTiO3, Na0.5Bi0.5TiO3, K0.5Bi0.5TiO3, Na0.5K0.5NbO3, and their solid solutions. The factors that contribute to strong piezoelectric behavior are described and a summary of the properties for the various systems is provided.

Lead-Free Hunting Rifle Ammunition: Product Availability, Price, Effectiveness, and Role in Global Wildlife Conservation

Thomas, Vernon George
Fonte: Springer Netherlands Publicador: Springer Netherlands
Tipo: Artigo de Revista Científica
EN
Relevância na Pesquisa
47.209243%
Proposals to end the use of lead hunting ammunition because of the established risks of lead exposure to wildlife and humans are impeded by concerns about the availability, price, and effectiveness of substitutes. The product availability and retail prices of different calibers of lead-free bullets and center-fire rifle ammunition were assessed for ammunition sold in the USA and Europe. Lead-free bullets are made in 35 calibers and 51 rifle cartridge designations. Thirty-seven companies distribute internationally ammunition made with lead-free bullets. There is no major difference in the retail price of equivalent lead-free and lead-core ammunition for most popular calibers. Lead-free ammunition has set bench-mark standards for accuracy, lethality, and safety. Given the demonstrated wide product availability, comparable prices, and the effectiveness of high-quality lead-free ammunition, it is possible to phase out the use of lead hunting ammunition world-wide, based on progressive policy and enforceable legislation.

Lead-Free Intravascular Ultrasound Transducer Using BZT-50BCT Ceramics

Yan, Xingwei; Lam, Kwok Ho; Li, Xiang; Chen, Ruimin; Ren, Wei; Ren, Xiaobing; Zhou, Qifa; Shung, K. Kirk
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em /06/2013 EN
Relevância na Pesquisa
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This paper reports the fabrication and evaluation of a high-frequency ultrasonic transducer based on a new lead-free piezoelectric material for intravascular imaging application. Lead-free 0.5Ba(Zr0.2Ti0.8)O3−0.5(Ba0.7Ca0.3)TiO3 (BZT-50BCT) ceramic with a high dielectric constant (~2800) was employed to develop a high-frequency (~30 MHz) needle-type ultrasonic transducer. With superior piezoelectric performance (piezoelectric coefficient d33 ~ 600 pC/N), the lead-free transducer was found to exhibit a −6-dB bandwidth of 53% with an insertion loss of 18.7 dB. In vitro intravascular ultrasound (IVUS) imaging of a human cadaver coronary artery was performed to demonstrate the potential of the lead-free transducer for biomedical imaging applications. This is the first time that a lead-free transducer has been used for IVUS imaging application. The experimental results suggest that the BZT-50BCT ceramic is a promising lead-free piezoelectric material for high-frequency intravascular imaging applications.

Electromechanical properties of engineered lead free potassium sodium niobate based materials; Propriedades electromecânicas de materiais à base de niobato de potássio e sódio

Rafiq, Muhammad Asif
Fonte: Universidade de Aveiro Publicador: Universidade de Aveiro
Tipo: Tese de Doutorado
ENG
Relevância na Pesquisa
67.018486%
K0.5Na0.5NbO3 (KNN), is the most promising lead free material for substituting lead zirconate titanate (PZT) which is still the market leader used for sensors and actuators. To make KNN a real competitor, it is necessary to understand and to improve its properties. This goal is pursued in the present work via different approaches aiming to study KNN intrinsic properties and then to identify appropriate strategies like doping and texturing for designing better KNN materials for an intended application. Hence, polycrystalline KNN ceramics (undoped, non-stoichiometric; NST and doped), high-quality KNN single crystals and textured KNN based ceramics were successfully synthesized and characterized in this work. Polycrystalline undoped, non-stoichiometric (NST) and Mn doped KNN ceramics were prepared by conventional ceramic processing. Structure, microstructure and electrical properties were measured. It was observed that the window for mono-phasic compositions was very narrow for both NST ceramics and Mn doped ceramics. For NST ceramics the variation of A/B ratio influenced the polarization (P-E) hysteresis loop and better piezoelectric and dielectric responses could be found for small stoichiometry deviations (A/B = 0.97). Regarding Mn doping...

Influence of PCB surface finish and thermal and temperature/humidity aging on the performance of a novel anisotropic conductive adhesive for lead-free surface mount assembly

Ramkumar, S. Manian; Srihari, Krishnaswami
Fonte: IEEE: Proceedings of the 57th Electronic Components & Technology Conference Publicador: IEEE: Proceedings of the 57th Electronic Components & Technology Conference
Tipo: Proceedings
EN_US
Relevância na Pesquisa
46.98275%
The electronics industry, in recent years, has been focusing primarily on product miniaturization and lead-free assembly. The need to eliminate lead-based materials as a means of interconnection has renewed the industry's interest in exploring other means of assembling surface mount devices reliably, especially using conductive adhesives. This paper will discuss the performance characteristics and research findings pertaining to a novel anisotropic conductive adhesive for lead-free electronics packaging applications. The applicability of the novel conductive adhesive in board level assembly has been demonstrated successfully. The IV characteristics and the breakdown current characteristics have shown the importance of achieving very low initial contact resistance after assembly, in order to enable longer life under thermal and temperature-humidity aging conditions. Thermal aging of the adhesive material has revealed improvement in contact resistance and temperature/humidity aging has shown deterioration in performance within the first 100 hours of aging. Area array packages with and without bumps have shown variations in performance and their has revealed the importance of placement pressure, placement speed and placement dwell in achieving low initial contact resistance. Preliminary experiment has shown that the HASL finish performs better than OSP. The experimental study presented in this paper examines the performance of the adhesive on various Printed Circuit Board (PCB) surface finishes which include Sn/Pb (HASL)...

Thermal cycle/aging reliability of lead free 0201 assemblies

Ghaffarian, Reza; Ramkumar, S. Manian; Varanasi, Arun
Fonte: IEEE: Proceedings of the 56th Electronic components & technology conference Publicador: IEEE: Proceedings of the 56th Electronic components & technology conference
Tipo: Proceedings
EN_US
Relevância na Pesquisa
67.142544%
This paper presents the test results and comparative literature data on the influence of a few key manufacturing parameters and defects associated with the 0201 components using lead-free and tin-lead solder alloys. A large number of test vehicles assembled with 0201 components were subjected to isothermal aging at 150°C and thermal cycling in the range of -55° to 100°C in order to establish their reliability. The shear tests were carried out at various aging intervals up to 500 hours to determine the effects of aging damage on the solder joint strength and this data will be presented and compared to virgin assemblies. Weibull plots will be given for reliability to establish solder joint aging behavior for the lead free assemblies compared to lead based solder as well as data correlation for various sets of data. Optical inspection photos taken during thermal cycling to establish damage progress, scanning electron microscopy (SEM) photos to reveal details of damage at 1500 cycles, and cross-sectional photomicrographs showing interconnect microstructural changes and intermetallic formation will also be presented.; ©2009 IEEE. Personal use of this material is permitted. However, permission to reprint/republish this material for advertising or promotional purposes or for creating new collective works for resale or redistribution to servers or lists...

Effect of deviating from the reflow process window for lead-free assembly

Ramkumar, S. Manian; Sampathkumar, Manivannan; Rajesnayagham, Santhakumar; Riyaz, Shaik; Anson, Scott
Fonte: SMTA: Journal of Surface Mount Technology Publicador: SMTA: Journal of Surface Mount Technology
Tipo: Artigo de Revista Científica
EN_US
Relevância na Pesquisa
67.02682%
The primary objective of this research is to determine the influence of deviating from the standard reflow process window for lead-free soldering. As the industry is moving towards lead-free technology, SAC solder alloy (melting point 217°C) is being viewed as a potential alternative to conventional Sn/Pb solder alloy (melting point 183°C). The higher melting point of lead-free solders demand higher reflow process temperature profiles. Since current electronic components can withstand a maximum temperature only in the range 245-250°C, the process window for reflow soldering has narrowed. It is expected that even minor deviations outside of the window could have a dramatic effect on the process outcome and the component's ability to function properly. In this research project, peak reflow temperature (Tpeak) and time above liquidus (TAL) were varied across the solder paste manufacturer recommended specifications (standard process window), in order to study the effect of process window deviation. Solder joint quality, shear strength, microstructure and intermetallic of the joints were used as metrics to determine the influence of deviating from the process window. Interestingly, across the process window, as peak temperature and TAL varied...

Lead-free 0201 assembly and reliability

Ramkumar, S. Manian; Newasekar, Rahul; Ghaffarian, Reza
Fonte: IEEE: Proceedings of the IEEE/CPMT International Symposium on Advanced Packaging Materials: Processes, Properties and Interfaces Publicador: IEEE: Proceedings of the IEEE/CPMT International Symposium on Advanced Packaging Materials: Processes, Properties and Interfaces
Tipo: Proceedings
EN_US
Relevância na Pesquisa
67.121396%
The many challenges with 0201 assembly can be attributed to the solder paste volume, pad design, aperture design, board finish, type of solder paste, pick and place and reflow profile. A Design of Experiment study was carried out to investigate the effects of these parameters on assembly defects and reliability. The test vehicles for the study consist of pad layouts for 2000-0201 components. Five different test vehicles were used, with the same pad layout and non-solder mask defined pads, with HASL, Ni/Au, Pure Tin (Sn), Immersion Silver (ImAg) and OSP finish. Four different pad shapes are designed on each of the test vehicles (rectangular, oval, modified home plate and double trapezoid). The pad areas for all four shapes are maintained the same. The pads are oriented both in the horizontal and vertical directions. Electroformed 3 mil and 4.65 mil thick stencils were used for printing the solder paste. The stencil was designed to obtain two distinct aperture-pad combinations (matched and unmatched). Three solder paste types (lead-based, lead-free and anti-tomstoning) were used in the study. Two test vehicles assembled for each experimental run, one with resistors and the other with capacitors, provided an understanding of the difference in the process for these two common passive devices. This paper will discuss in detail the influence of a few key parameters and defects associated with them using both leaded and lead free solder alloys. The most recent data on shear test results after isothermal aging at 150ºC will be presented.; ©2005 IEEE. Personal use of this material is permitted. However...

Lead-free soldering processes in the electronic industry: industrial implementation at SMES

Carmo,Rolim do; Pinto,Margarida; Colaço,Rogério; Andersson,Dag
Fonte: Sociedade Portuguesa de Materiais Publicador: Sociedade Portuguesa de Materiais
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/07/2007 EN
Relevância na Pesquisa
67.15954%
Following the implementation of the new European environmental directives, Restriction of the Use of Certain Hazardous Substances (RoHS) and Waste Electrical and Electronic Equipment (WEEE), which involve the ban of lead from electronic and electrical products, this work presents process development work, production and reliability testing of real products from several electric and electronic assemblers using lead-free commercial solders that have been tested and monitored to ensure the reliability of the final products. The results were compared with the ones using tin/lead solders, in terms of performance and reliability of the joints obtained. This work aims to help the implementation of the lead-free solders in the soldering processes and supply the SMEs more information about real products and conditions that might be compared with theirs. The reliability tests and characterisation of the real products from several companies showed that the lead-free boards demonstrated a good performance under testing, being equivalent or better than the tin/lead ones. The defects or anomalies found in most of the joints (voiding and pad lifting) result from the manufacturing process. Most of the defects were found in through-hole devices and were due to component failures and not from the joint integrity. The degradation after the reliability tests of both types of solders is similar. The SMEs are engaged in taking this opportunity to reach a higher quality performance level in their processes. Some of the companies embraced this “forced” transition to upgrade and improve their process and facilities...

; ; ; ; Lead environmental issues and new solder alloys in electro-electronics equipment

Grigoletto, Eliane Maria; Pécora, Araí Augusta Bernardez
Fonte: Labor & Engenho; Labor & Engenho Publicador: Labor & Engenho; Labor & Engenho
Tipo: info:eu-repo/semantics/article; info:eu-repo/semantics/publishedVersion; Artigo Avaliado pelos Pares; análise química Formato: application/pdf
Publicado em 01/12/2013 ENG
Relevância na Pesquisa
56.81198%
; ; ; ; The use of Surface Mounted Technology (SMT) and the miniaturization of the electronics equipment are demanding new lead-free materials in the soldering process, due to its high toxicity to human being and environmental concerns. Global competitiveness has been driving industries to technological development as challenges to the manufactures and there is an effort to use alternative materials for the soldering electronic components to find an environment-friendly process. This paper presents a literature review involving soldering processes and describes the lead toxicity from related residue. The main solder alloy that is nowadays used to substitute tin-lead and European Directives are also presented.