ANALYSIS OF RELIABILITY AND CONDUCTION MECHANISMS IN EMBEDDED PLANAR CAPACITORS

An embedded planar capacitor is a thin laminate embedded in a multilayered printed wiring board (PWB) that functions both as a power-ground plane and as a parallel plate capacitor. The capacitor laminate consists of a dielectric material (epoxy-BaTiO3 composite dielectric is widely used) sandwiched between two Cu layers. These capacitors have gained importance with an increase in the operating frequency and a decrease in the supply voltage in electronic circuits since it can lead to PWB miniaturization. Further, the use of embedded planar capacitor leads to better electrical performance of the PWB. Although embedded planar capacitors have various advantages there are some issues such as lack of reliability information and a high leakage current in the epoxy-BaTiO3 composite dielectric. This dissertation aims in investigating these issues that needs to be investigated for wide scale commercialization of these capacitors. The reliability of embedded planar capacitors is critical since these capacitors are not reworkable and its failure can lead to PWB failure. In this work the reliability of an embedded planar capacitor (with epoxy-BaTiO3 composite dielectric) is investigated under environmental stress conditions in the presence of an applied bias. Temperature-humidity-bias (THB) tests and highly accelerated life test (HALT) was performed at multiple stress levels to investigate the reliability under these conditions. The failure modes and mechanisms during THB and HALT are investigated. Further, during HALT the life time is also modeled using the Prokopowicz model and regression of the in-situ capacitor data. The loading of BaTiO3 in the epoxy-BaTiO3 composite dielectric should be as high as possible (until the theoretical maximum packing density is achieved) to maximize the effective dielectric constant of the composite. But as the loading of BaTiO3 in the composite dielectric increases, the undesirable leakage current also increases. The mechanism of current conduction in this composite dielectric is investigated in this work. The effect of various factors such as BaTiO3 loading, BaTiO3 particle diameter, temperature, and voltage on the resulting leakage current has been modeled. Measurements of leakage current were performed on embedded capacitors with varying BaTiO3 loading and varying particle diameters over a range of temperature and voltage. The consistence of the leakage current data with standard conduction models is compared to investigate the conduction mechanism

Preparation and Characterization of Calcium Copper Titanate Filled Epoxy Composites for Embedded Capacitor Applications

Permintaan yang semakin meningkat untuk pengecilan peranti elektronik menawarkan pengurangan saiz yang ketara, prestasi dielektrik dan haba yang lebih baik, kebolehpercayaan dan kos yang lebih rendah. Komposit polimer-seramik telah dipilih sebagai bahan dielektrik yang paling sesuai untuk kapasitor terbenam. Dalam kajian ini, seramik seperti kalsium kuprum titanat, CaCu3Ti4O12 (CCTO) dan barium titanat (BaTiO3) telah digunakan sebagai pengisi dalam komposit epoksi filem nipis. Sifat-sifat komposit epoksi filem nipis dihasilkan berdasarkan muatan pengisi yang berbeza (5 hingga 20% isipadu), kaedah fabrikasi seperti salutan putaran (SC) dan tekan panas (HP), pengisi hibrid (CCTO dan BaTiO3), rawatan permukaan pengisi dan pelbagai jenis resin epoksi (DER 332, Epolam 2015 dan OP 392) telah dikaji. Keputusan menunjukkan bahawa komposit CCTO/epoksi mempamerkan pemalar dielektrik, Tg dan kekonduksian haba yang lebih tinggi berbanding dengan epoksi tidak terisi dan komposit BaTiO3/epoksi. Dalam siri kedua, pengisi CCTO untuk pengisian komposit epoksi telah dipilih untuk siasatan lanjutan. Komposit CCTO/epoksi dengan pengisian sehingga 40% isipadu dapat dihasilkan dengan menggunakan kaedah HP. Hasil ujian telah menunjukkan bahawa sifat-sifat komposit 40% isipadu CCTO/epoksi (HP) telah meningkat sebanyak 55% pemalar dielektrik dan 83% modulus simpanan, dan penurunan 69% pekali pengembangan haba berbanding dengan sifat-sifat komposit 20% isipadu CCTO/epoksi (SC). Pengisi Hibrid untuk pengisian komposit epoksi telah dihasilkan dan keputusan menunjukkan bahawa Hibrid 70:30 mempamerkan kesan hibrid yang positif berbanding dengan komposit pengisi tunggal; komposit filem nipis CCTO/epoksi dan BaTiO3/epoksi. Selepas rawatan CCTO oleh ejen gandingan silana, sampel komposit epoksi terisi CCTO 10% yang terawat menunjukkan peningkatan yang memberangsangkan iaitu sebanyak 60% pemalar dielektrik berbanding komposit filem nipis CCTO/epoksi yang tidak terawat. Berdasarkan pelbagai resin epoksi, komposit filem nipis CCTO/epoksi OP 392 yang terawat mempamerkan kenaikan pemalar dielektrik sebanyak 10% dan susutan dalam pekali pengembangan haba sebanyak 38% berbanding dengan bahan dielektrik komersial, iaitu 3M Embedded Capacitor. Secara kesimpulannya, komposit filem nipis CCTO/epoksi OP 392 yang terawat menunjukkan prestasi yang baik dari segi pemalar dielektrik dan haba berbanding komposit CCTO yang tidak terawat, komposit hibrid dan lain-lain komposit terawat. ________________________________________________________________________________________________________________________ Continuous miniaturization of electronic devices result in a high demand of embedded capacitor that offers significant reduction in size, better dielectric and thermal performance, reliability and lower cost. Polymer-ceramic composites have been considered as the most suitable dielectric materials for embedded capacitor. In this study, ceramics such as calcium copper titanate, CaCu3Ti4O12 (CCTO) and barium titanate (BaTiO3) were used as fillers in epoxy thin film composites. The properties of epoxy thin film composites fabricated based on different filler loading (5 to 20 vol%), fabrication methods such as spin coating (SC) and hot press (HP) methods, hybrid fillers (CCTO and BaTiO3), surface treatment of filler and various types of epoxy resins (DER 332, Epolam 2015 and OP 392) were characterized. Results showed that CCTO/epoxy composite exhibited higher dielectric constant, Tg and thermal conductivity compared to those of unfilled epoxy and BaTiO3/epoxy composites. In the second series, CCTO filler filled epoxy composite was chosen for further investigation. CCTO/epoxy composite with filler loading of up to 40 vol% was able to be produced by using HP method. It was found that 40 vol% CCTO/epoxy (HP) composite has increased 55% of dielectric constant and 83% of storage modulus, and decreased 69% of CTE compared to 20 vol% CCTO/epoxy (SC) composite. Hybrid fillers composites were fabricated and results indicated that Hybrid 70:30 showed positive hybrid effect compared to those of single filler composites; CCTO/epoxy and BaTiO3/epoxy thin film composites. After treatment of CCTO by silane-based coupling agent, sample with 10% treated CCTO filled epoxy composite presented remarkable improvement with an increased 60% of dielectric constant than untreated CCTO/epoxy thin film composite. Based on various epoxy resins, treated CCTO/OP 392 epoxy thin film composite has improved 10% of dielectric constant and decreased 38% of CTE compared to 3M Embedded Capacitor. In short, treated CCTO filled OP 392 epoxy thin film composite exhibited good dielectric properties and thermal properties compared to those of untreated CCTO composites, hybrid fillers composites and other treated composites

Preparation and Characterization of Calcium Copper Titanate Filled Epoxy Composites for Embedded Capacitor Applications

Permintaan yang semakin meningkat untuk pengecilan peranti elektronik menawarkan pengurangan saiz yang ketara, prestasi dielektrik dan haba yang lebih baik, kebolehpercayaan dan kos yang lebih rendah. Komposit polimer-seramik telah dipilih sebagai bahan dielektrik yang paling sesuai untuk kapasitor terbenam. Dalam kajian ini, seramik seperti kalsium kuprum titanat, CaCu3Ti4O12 (CCTO) dan barium titanat (BaTiO3) telah digunakan sebagai pengisi dalam komposit epoksi filem nipis. Sifat-sifat komposit epoksi filem nipis dihasilkan berdasarkan muatan pengisi yang berbeza (5 hingga 20% isipadu), kaedah fabrikasi seperti salutan putaran (SC) dan tekan panas (HP), pengisi hibrid (CCTO dan BaTiO3), rawatan permukaan pengisi dan pelbagai jenis resin epoksi (DER 332, Epolam 2015 dan OP 392) telah dikaji. Keputusan menunjukkan bahawa komposit CCTO/epoksi mempamerkan pemalar dielektrik, Tg dan kekonduksian haba yang lebih tinggi berbanding dengan epoksi tidak terisi dan komposit BaTiO3/epoksi. Dalam siri kedua, pengisi CCTO untuk pengisian komposit epoksi telah dipilih untuk siasatan lanjutan. Komposit CCTO/epoksi dengan pengisian sehingga 40% isipadu dapat dihasilkan dengan menggunakan kaedah HP. Hasil ujian telah menunjukkan bahawa sifat-sifat komposit 40% isipadu CCTO/epoksi (HP) telah meningkat sebanyak 55% pemalar dielektrik dan 83% modulus simpanan, dan penurunan 69% pekali pengembangan haba berbanding dengan sifat-sifat komposit 20% isipadu CCTO/epoksi (SC). Pengisi Hibrid untuk pengisian komposit epoksi telah dihasilkan dan keputusan menunjukkan bahawa Hibrid 70:30 mempamerkan kesan hibrid yang positif berbanding dengan komposit pengisi tunggal; komposit filem nipis CCTO/epoksi dan BaTiO3/epoksi. Selepas rawatan CCTO oleh ejen gandingan silana, sampel komposit epoksi terisi CCTO 10% yang terawat menunjukkan peningkatan yang memberangsangkan iaitu sebanyak 60% pemalar dielektrik berbanding komposit filem nipis CCTO/epoksi yang tidak terawat. Berdasarkan pelbagai resin epoksi, komposit filem nipis CCTO/epoksi OP 392 yang terawat mempamerkan kenaikan pemalar dielektrik sebanyak 10% dan susutan dalam pekali pengembangan haba sebanyak 38% berbanding dengan bahan dielektrik komersial, iaitu 3M Embedded Capacitor. Secara kesimpulannya, komposit filem nipis CCTO/epoksi OP 392 yang terawat menunjukkan prestasi yang baik dari segi pemalar dielektrik dan haba berbanding komposit CCTO yang tidak terawat, komposit hibrid dan lain-lain komposit terawat. ________________________________________________________________________________________________________________________ Continuous miniaturization of electronic devices result in a high demand of embedded capacitor that offers significant reduction in size, better dielectric and thermal performance, reliability and lower cost. Polymer-ceramic composites have been considered as the most suitable dielectric materials for embedded capacitor. In this study, ceramics such as calcium copper titanate, CaCu3Ti4O12 (CCTO) and barium titanate (BaTiO3) were used as fillers in epoxy thin film composites. The properties of epoxy thin film composites fabricated based on different filler loading (5 to 20 vol%), fabrication methods such as spin coating (SC) and hot press (HP) methods, hybrid fillers (CCTO and BaTiO3), surface treatment of filler and various types of epoxy resins (DER 332, Epolam 2015 and OP 392) were characterized. Results showed that CCTO/epoxy composite exhibited higher dielectric constant, Tg and thermal conductivity compared to those of unfilled epoxy and BaTiO3/epoxy composites. In the second series, CCTO filler filled epoxy composite was chosen for further investigation. CCTO/epoxy composite with filler loading of up to 40 vol% was able to be produced by using HP method. It was found that 40 vol% CCTO/epoxy (HP) composite has increased 55% of dielectric constant and 83% of storage modulus, and decreased 69% of CTE compared to 20 vol% CCTO/epoxy (SC) composite. Hybrid fillers composites were fabricated and results indicated that Hybrid 70:30 showed positive hybrid effect compared to those of single filler composites; CCTO/epoxy and BaTiO3/epoxy thin film composites. After treatment of CCTO by silane-based coupling agent, sample with 10% treated CCTO filled epoxy composite presented remarkable improvement with an increased 60% of dielectric constant than untreated CCTO/epoxy thin film composite. Based on various epoxy resins, treated CCTO/OP 392 epoxy thin film composite has improved 10% of dielectric constant and decreased 38% of CTE compared to 3M Embedded Capacitor. In short, treated CCTO filled OP 392 epoxy thin film composite exhibited good dielectric properties and thermal properties compared to those of untreated CCTO composites, hybrid fillers composites and other treated composites

Improvement of insulation effectiveness of natural rubber by adding hydroxyl-functionalized barium titanate nanoparticles

Natural rubber (NR) products are being applied in many protective tools for life-line applications, including insulating boots, blankets, sleeves, insulating gloves, or flexible coverings. Due to the inherent risk of such works it is imperative ensuring the quality of the safety products involved. The dielectric properties of NR-based products rely heavily on the compounding formulation and manufacturing processes involved. Considerable efforts are being applied to improve the dielectric performance of NR formulations to ensure that maintenance personnel work in the safer and most comfortable conditions. This work studies the addition of different weight fractions of surface-modified BaTiO3-OH nanoparticles to NR formulations to enhance dielectric properties such as breakdown strength and leakage current. The results presented in this work show that the addition of a low weight fraction of surface-modified BaTiO3-OH nanofillers (= 1 wt.%) enhances the surface and volume resistivity, crystallinity, breakdown strength under ac conditions and lowers the leakage current under dc stress.Peer ReviewedPostprint (author's final draft

Anisotropic composite elaboration and modeling: toward materials adapted to systems

L'objectif de ces travaux de thèse a été de démontrer la possibilité, en se basant sur une approche prédictive, de contrôler avec précision la fonctionnalisation d'un matériau composite, d'isotrope à anisotrope, sous l'application d'un champ électrique. Ces derniers matériaux présentent en effet un fort potentiel pour des applications futures telles que des condensateurs intégrés ou bien encore des composites conducteurs thermiques. Une première approche théorique des différentes forces et mécanismes entrant en jeux lors de l'élaboration de composites anisotropes par chaînage a permis d'identifier les paramètres impactant le procédé d'élaboration. A la suite de cette étude théorique, un modèle de formation de chaînes de particules sous champ électrique a été développé afin de prédire la dynamique de chaînage. Le modèle choisi (méthode moment dipolaire effectif) a permis la simulation de plus de 4500 particules. Les paramètres ayant au préalable été identifiés ont ensuite été mesurés. Pour la permittivité des particules, une méthode de mesure diélectrophorétique a été développée, ce qui est une première dans le cas de particules céramiques. L'élaboration des composites anisotropes a été couplé avec un suivi novateur, en temps réel, d'un marqueur (permittivité) de la formation de chaînes, permettant d'obtenir la dynamique de structuration des particules. Afin de valider l'aspect prédictif du modèle numérique, une comparaison a été effectuée entre la dynamique mesurée et simulée. Les résultats obtenus ont démontré une très bonne fiabilité des prédictions du modèle, même si des progrès sont encore réalisables aux faibles taux de chargement. Dans un dernier temps, une preuve de concept a été démontrée, de la réalisation de composites anisotropes dont les particules sont alignées perpendiculairement au champ électrique.This study was aimed to demonstrate the possibility, based on a predictive approach, to tailor the structure of a composite from isotropic to anisotropic when applying an electric field. This composites have great potential for future applications such as embed capacitors or thermally conductive composites. A theoretical approach of the forces and mechanisms acting in the elaboration of anisotropic composites by chaining allowed identifying the key parameters. Based on this approach a model of particle chaining under electric field was established to predict the structuration dynamics. This model (effective dipole moment) allowed simulating more than 4500 particles. The parameters previously identified were then measured, and for the particle permittivity, a dielectrophoretic measurement method was developed, which was a first for ceramic particles. The elaboration of anisotropic composites was coupled to a novel on-line monitoring of a chaining marker (permittivity), allowing to obtain the structuration dynamics. To validate the predictive aspect of the model, experimental and numerical dynamics were compared showing the robustness and accuracy of the model, even if improvement is still possible at low filler content. In the last part, a proof of concept was demonstrated of the elaboration of anisotropic composites with fillers oriented normally to the direction of the electric field

Functional nanocomposites for energy storage: chemistry and new horizons

Energy storage devices are one of the hot spots in recent years due to the environmental problems caused by the large consumption of unsustainable energy such as petroleum or coal. Capacitors are a common device for energy storage, especially electrical energy. A variety of types including electrolytic capacitors, mica capacitors, paper capacitors, ceramic capacitors, film capacitors, and non-polarized capacitors have been proposed. Their specific applications depend on their intrinsic properties. Dielectric capacitors have reasonable energy storage density, with current research focusing on the enhancement of energy density and making the materials more flexible as well as lightweight. Improvement strategies are based on the premise that use of two or more different materials (e.g. polymers and ceramics/metals) at an optimal formulation can result in properties that combine the advantages of the precursor materials. Different polymers especially fluoropolymers (e.g. PVDF and PVDF based co-polymer) are the main components in dielectric nanocomposites for capacitors with high energy storage performance. In this article, we have briefly summarized the recent advances in functional polymers nanocomposites for energy storage applications with a primary focus on polymers, surface engineering, functional groups and novel synthesis/manufacturing concepts applied to new materials. The article presents a unique integrated structure and approaches providing key knowledge for the design and development of novel, low-cost, multifunctional next-generation energy storage materials with improved efficiency