Yang Rao

A precise numerical prediction of effective dielectric constant for polymer-ceramic composite based on effective-medium theory

Nanostructure polymer-ceramic composite with high dielectric constant (/spl epsiv//sub /spl tau///spl sim/90) has been developed for embedded capacitor application. This polymer-ceramic system consists of lead magnesium niobate-lead titanate (PMN-PT) ceramic particle and modified high-dielectric constant low-viscosity epoxy resin. In order to obtain precise prediction of effective dielectric constant of this composite, an empirical prediction model based on self-consistent theory is proposed. The electrical polarization mechanism and interaction between epoxy resin and ceramic filler has been studied. This model can establish the relevant constitutional parameters of polymer-ceramic composite materials such as particle shape, composition, and connectivity that determine the dielectric properties of the composite. This model is simpler, uses fewer parameters and its prediction compares better with experiment (error <10%). The precision and simplicity of the model can be exploited for predictions of the properties and design of nanostructure ferroelectric polymer-ceramic composites. The effective-medium theory (EMT) has been proved a good tool to predict effective properties of nanocomposites.

An improved methodology for determining temperature dependent moduli of underfill encapsulants

Finite element analyses (FEAs) have been widely used to preventively predict the reliability issues of flip-chip (FC) packages. The validity of the simulation results strongly depends on the inputs of the involved material properties. For FC packages Youngs modulus-temperature relationship is a critical material property in predicting of the package reliability during -55/spl deg/C to 125/spl deg/C thermal cycling. Traditional tensile tests can obtain the modulus at selected temperatures, but are tedious, expensive, and unable to accurately predict the Youngs modulus-temperature relationship within a wide temperature range. Thus, this paper is targeted to provide a simple but relatively accurate methodology to obtain the Youngs modulus-temperature relationship. In this paper, three commercial silica filled underfill materials were studied. A simple specimen (based on ASTM D638M) preparation method was established using a Teflon mold. A dynamic-mechanical analyzer (DMA) was used to obtain the stress-strain relationship under controlled force mode, storage and loss modulus under multi-frequency mode, and stress relaxation under stress relaxation mode. A simple viscoelastic model was used and an empirical methodology for obtaining Youngs modulus-temperature relationship was established.

Di-block copolymer surfactant study to optimize filler dispersion in high dielectric constant polymer-ceramic composite

Embedded capacitor technology can improve electrical performance and reduce assembly cost compared with traditional discrete capacitor technology. Polymer-ceramic composites have been of great interest as embedded capacitor material because they combine the processability of polymers with the desired electrical properties of ceramics. Dispersion of ceramic particles is a critical factor to affect the effective dielectric constant of polymer-ceramic composite. Di-block copolymer surfactants have been used to prevent agglomeration of the ceramic particles. It was found that di-block copolymer surfactant could improve the ceramic dispersion better than monomer surfactant. Using di-block copolymer surfactant, higher dielectric constant was achieved at lower ceramic loading level. This high dielectric constant polymer-ceramic composite material has much better mechanical properties and can be used for the integral capacitors in the SOP (system on a package) substrate.

High K polymer-ceramic nano-composite development, characterization, and modeling for embedded capacitor RF application

Embedded capacitor technology can improve electrical performance and reduce assembly cost compared with traditional discrete capacitor technology. Polymer-ceramic composites have been of great interest as embedded capacitor material because they combine the processability of polymers with the desired electrical properties of ceramics. A novel nano-structure polymer-ceramic composite with very high dielectric constant (/spl epsiv//sub /spl tau//=150) has been developed in this work. RF application of embedded capacitors requires that insulating material have high dielectric constant in higher frequency (GHz), low leakage current, high breakdown voltage and high reliability. A set of electric tests have been conducted in this work to characterize the properties of the in house developed novel high dielectric constant polymer-ceramic nano-composite. Results show that this material has fair high dielectric constant in RF range, low electric leakage and high breakdown voltage. An embedded capacitor prototype with capacitance density of 35 nF/cm/sup 2/ has been manufactured using this nano-composite and spinning coating technology. The design of embedded passives is very important to its practical application. The commercial finite element software ANSYS and electric simulation software SPICE were used for the simulation of embedded capacitor performance in the RF range. This novel nano-composite can be used for the integral capacitors in the RF applications.

Ultra high dielectric constant epoxy silver composite for embedded capacitor application

Embedded capacitor technology can increase silicon packaging efficiency, improve electrical performance, and reduce electronic assembly cost compared with traditional discrete capacitor technology. Developing a suitable material that satisfies electrical, reliability and processing requirements is one of the major challenges of incorporating capacitors into a printed wiring board (PWB) for demanding wireless, RF portable telecommunication products. A novel epoxy-based composite with very ultra high dielectric constant (/spl epsiv//sub r//spl sim/1000) has been developed in this work. The previous record of /spl epsiv//sub r/=150 was only recently reported. To our best knowledge, this is the highest K value of the polymer-based composite ever reported. High dielectric constant is obtained by increasing the concentration of conductive filler close to but not exceed the percolation threshold within the polymer matrix. This novel ultra high K material also has low dielectric loss (<0.02), good adhesion and perfect multi-chip-module laminate (MCM-L) process compatibility. This novel composite is the perfect material candidate for the integral embedded capacitor applications for next generation electronic products.

Novel high dielectric constant nano-structure polymer-ceramic composite for embedded capacitor application

Embedded capacitor technology can improve electrical performance and reduce assembly cost compared with traditional discrete capacitor technology. Developing a suitable material that satisfies electrical, reliability and processing requirements is one of the major challenges of incorporating capacitors into a print wire board (PWB). Polymer-ceramic composites have been of great interest as embedded capacitor material because they combine the processability of polymers with the desired electrical properties of ceramics. A novel nano-structure polymer-ceramic composite with very high dielectric constant (/spl epsi//sub r/-100, a new record for the highest reported /spl epsi//sub r/ value of nano-composite) has been developed in this work. High dielectric constant is obtained by increasing the dielectric constant of the epoxy matrix (/spl epsi//sub r/>6) and using the combination of PMN-PT/BaTiO/sub 3/ as ceramic filler. This nano-composite has low curing temperature (<200/spl deg/C), thus it is MCM-L (multi-chip-module laminate) process compatible. An embedded capacitor prototype with capacitance density of 25 nF/cm/sup 2/ has been manufactured using this nano-composite and spinning coating technology. The effect of composite microstructure on the effective dielectric constant has been studied. This novel nanocomposite can be used for the integral capacitors as an important component of SOP (system on packaging) technology that is proposed by packaging research center of Georgia Tech.

High dielectric constant polymer-ceramic composite for embedded capacitor application

Integral passive components can reduce assembly cost and improve electrical performance as compared with traditional discrete passive components. Developing a suitable material that satisfies electrical, reliability, and processing requirements is one of the major challenges of incorporating passives into a print wire board (PWB). Polymer-ceramic composites have been of as much interest as integral capacitor materials because they combine the processability of polymers with the desired electrical properties of ceramics. In this work a polymer-ceramic composite with very high dielectric constant (/spl epsi//sub r/=89) has been developed for embedded capacitor application. High dielectric constant material is obtained by increasing the dielectric constant of the epoxy matrix (/spl epsi//sub r//spl sim/5) and using the combination of PMN-PT/BaTiO/sub 3/ as ceramic fillers. The effect of the composite microstructure on the effective dielectric constant has been studied.

A novel ultra high dielectric constant epoxy silver composite for embedded capacitor application

Embedded capacitor technology can increase silicon efficiency of the electronic packaging, improve electrical performance, and reduce electronic assembly cost compared with traditional discrete capacitor technology. Developing a suitable material that satisfies electrical, reliability and processing requirements is one of the major challenges of incorporating capacitors into a printed wiring board (PWB) for demanding wireless, RF portable telecommunication products. A novel epoxy-based composite with very ultra high dielectric constant (/spl epsiv//sub r//spl sim/1000) has been developed in this work. The previous record of /spl epsiv//sub r/=150 was only recently reported. To our best knowledge, this is the highest K value of the polymer-based composite ever reported. High dielectric constant is obtained by increasing the concentration of conductive filler close to but not exceed the percolation threshold within the polymer matrix. This novel ultra high K material also has low dielectric loss (<0.02), good adhesion and perfect multi-chip-module laminate (MCM-L) process compatibility. This novel composite is the perfect material candidate for the integral embedded capacitor applications for next generation electronic products.

Effective dielectric constant prediction of polymer-ceramic composite based on self-consistent theory

Nanostructure polymer-ceramic composite with high dielectric constant (/spl epsi//sub r//spl sim/100) has been developed for embedded capacitor application. This polymer-ceramic system consists of lead magnesium niobate-lead titanate (PMN-PT) ceramic particle and modified high dielectric low viscosity epoxy resin. In order to obtain precise prediction of effective dielectric constant of this composite, a closed form prediction model based on self-consistent theory is proposed. The electrical polarization mechanism and interaction between epoxy resin and ceramic filler has been studied. This model can establish the relevant constitutional parameters of polymer-ceramic composite materials such as particle shape, composition, and connectivity that determine the dielectric properties of the composite. This model is simpler, uses fewer parameters and its prediction compares better with experiment (error<10%). The precision and simplicity of the model can be exploited for predictions of the properties and design of nano-structure ferroelectric polymer-ceramic composites. Self-consistent theory has been proved a good tool to predict effective properties of nano-composites.

Use of dispersant in high K polymer-ceramic nano-composite to improve manufacturability and performance of integral capacitors

Integral or embedded capacitor technology could increase packaging density, improve electrical performance and reduce assembly cost compared with traditional discrete capacitor technology. Developing a successful dielectric material that satisfies electrical, reliability and processing requirements is one of the major challenges for incorporating capacitors into the large-area substrates. Polymer-ceramic nano-composites have been of great interest as the high dielectric constant (K) material because they combine the processability of polymers with the desired electrical properties of ceramics. Nevertheless, there are some technical barriers for the polymer-ceramic composites to be used in the organic substrates. Most significantly, for a very high dielectric constant of about 150 as reported so far by our group, a necessary rather high ceramic filler loading (85% by volume) gave problems in well dispersion of the ceramic fillers within the organic matrix, and there was almost no adhesion towards other layers in the printed circuit board structure. In order to develop polymer-ceramic nano-composites with a dielectric constant as high as possible together with compatibility toward manufacturing process of organic printed circuit boards, we have introduced dispersants into the formulations. Comprehensive formulation techniques have resulted in a much higher dielectric constant (e.g., typically over 65 at a ceramic loading of 40% by volume) as well as excellent adhesion performance.