Multilayer embedded passives (resistors, inductors, and capacitors) on a printed wiring board can help to meet high performance requirements at a low cost and at a smaller size. Such an integration of embedded passives has new challenges with respect to design, materials, manufacturing, thermal management and reliability. As the area of integral passives on printed circuit boards is relatively new, there is inadequate literature on the thermo-mechanical reliability of integral passives. Therefore, there is a compelling need to understand the thermo-mechanical reliability of integral passives through the development of physics-based models as well as through experiments, and this thesis aims to develop such an experimental and theoretical program to study the thermo-mechanical reliability of integral passives.. As integral passives are often composite layers with dissimilar material properties compared to the other layers in the integral substrate, it is essential to ensure that RLC characteristics of the embedded passives do not deteriorate with thermal cycling due to thermo-mechanical deformations. This thesis aims to study the changes in the passive characteristics due to the thermally-induced deformations. Embedded capacitors and inductors have been looked at specifically in this research. Multi-field physics-based models have been constructed to determine the change in electrical parameters after thermal cycling. The thermo-mechanical models assume direction-dependent material properties for the board substrate and interconnect copper layers and temperature-dependent properties for interlayer dielectric and passive layers. Using the deformed geometry, the electrical characteristics have been determined at low frequency. In parallel to the models, test vehicle substrates have been subjected to 1000 thermal cycles between -55??o 125??nd high humidity and temperature conditions at 85??5RH for 500 hours, and it has been observed that there are significant changes in the electrical parameters. The results obtained from the physics-based simulations have been validated against the measured electrical characteristics from the fabricated functional test boards that have been thermal cycled.

The thesis is mainly divided into three parts. The first part will discuss about structures, manufacture, and design flow of embedded passives in organic and flexible substrates, and the results of measurement and electromagnetic (EM) simulation will be compared as well. Second part will discuss the theory and the process of establishing broadband model, and the broadband model will be compared to Pi model and EM simulation. In the third part, we will try to design embedded bandpass filters in organic substrate by the experience of establishing the library of embedded passives. Because of lacking of the fabrication of large capacitance devices in organic substrate, we design bandpass filters by using T type in order to limit the lump devices in the larger inductance and smaller capacitance. The final result of the filters are small in size and have high performance, thus they can be well applied to the RF system in chip (SIP) of wireless communication.

In a typical printed circuit board assembly, over 70 percent of the electronic components are passives such as resistors, inductors, and capacitors, and these passives could take up to 50 percent of the entire printed circuit board area. By embedding the passive components within the substrate instead of being mounted on the surface, the embedded passives could reduce the system real estate, eliminate the need for surface-mounted discrete components, eliminate lead based interconnects, enhance electrical performance and reliability, and potentially reduce the overall cost. Even with these advantages, embedded passive technology, especially for organic substrates, is at an early stage of development, and thus a comprehensive experimental and theoretical modeling study is needed to understand the fabrication and reliability of embedded passives before they can be widely used. This thesis aims to fabricate embedded passives in a multilayered organic substrate, perform extensive electrical and mechanical reliability tests, and develop physics-based models to predict the thermo-mechanical reliability of embedded capacitors. Embedded capacitors and resistors with different geometric shapes, planar dimensions, and thus different electrical characteristics have been fabricated on two different test vehicles. Capacitors are made with polymer/ceramic nanocomposite materials and have a capacitance in the range of 50 pF to 1.5 nF. Resistors are carbon ink based Polymer Thick Film (PTF) and NiCrAlSi and have a resistance in the range of 25 to 400 k. High frequency measurements have been done using Vector Network Analyzer (VNA) with 2 port signal-ground (S-G) probes. Accelerated thermal cycling (-55 to 125oC) and constant temperature and humidity tests (85oC/85RH) based on JEDEC and MIL standards have been performed. Furthermore, physics-based numerical models have been developed and validated using the experimental data. By focusing on the design and fabrication as well as the experimental and theoretical reliability assessments, this thesis aims to contribute to the overall development of embedded passive technology for Digital and Radio Frequency (RF) applications.

Driven by ever growing demands of miniaturization, increased functionality, high performance and low cost for microelectronic products and packaging, embedded passives will be one of the key emerging techniques for realizing the system integration which offer various advantages over traditional discrete components. Novel materials for embedded capacitor applications are in great demand, for which a high dielectric constant (k), low dielectric loss and process compatibility with printed circuit boards are the most important prerequisites. To date, no available material satisfies all these prerequisites and research is needed to develop materials for embedded capacitor applications. Conductive filler/polymer composites are likely candidate material because they show a dramatic increase in their dielectric constant close to the percolation threshold. One of the major hurdles for this type of high-k composites is the high dielectric loss inherent in these systems. In this research, material and process innovations were explored to design and develop conductive filler/polymer nanocomposites based on nanoparticles with controlled parameters to fulfill the balance between sufficiently high-k and low dielectric loss, which satisfied the requirements for embedded decoupling capacitor applications. This work involved the synthesis of the metal nanoparticles with different parameters including size, size distribution, aggregation and surface properties, and an investigation on how these varied parameters impact the dielectric properties of the high-k nanocomposites incorporated with these metal nanoparticles. The dielectric behaviors of the nanocomposites were studied systematically over a range of frequencies to determine the dependence of dielectric constant, dielectric loss tangent and dielectric strength on these parameters.

The integration of mixed-signal systems has long been a problem in the semiconductor industry. CMOS System-on-Chip (SOC), the traditional means for integration, fails mixed-signal systems on two fronts; the lack of on-chip passives with high quality (Q) factors inhibits the design of completely integrated wireless circuits, and the noise coupling from digital to analog circuitry through the conductive silicon substrate degrades the performance of the analog circuits. Advancements in semiconductor packaging have resulted in a second option for integration, the System-On-Package (SOP) approach. Unlike SOC where the package exists just for the thermal and mechanical protection of the ICs, SOP provides for an increase in the functionality of the IC package by supporting multiple chips and embedded passives. However, integration at the package level also comes with its set of hurdles, with significant research required in areas like design of circuits using embedded passives and isolation of noise between analog and digital sub-systems. A novel multiband balun topology has been developed, providing concurrent operation at multiple frequency bands. The design of compact wideband baluns has been proposed as an extension of this theory. As proof-of-concept devices, both singleband and wideband baluns have been fabricated on Liquid Crystalline Polymer (LCP) based organic substrates. A novel passive-Q based optimization methodology has been developed for chip-package co-design of CMOS Low Noise Amplifiers (LNA). To implement these LNAs in a mixed-signal environment, a novel Electromagnetic Band Gap (EBG) based isolation scheme has also been employed. The key contributions of this work are thus the development of novel RF circuit topologies utilizing embedded passives, and an advancement in the understanding and suppression of signal coupling mechanisms in mixed-signal SOP-based systems. The former will result in compact and highly integrated solutions for RF front-ends, while the latter is expected to have a significant impact in the integration of these communication devices with high performance computing.

Conventionally discrete passive components like capacitors, resistors, and inductors are surface-mounted on top of the printed circuit boards (PCBs). To match the ever increasing demands of miniaturization, cost reduction, and high performance in microelectronic industry, a promising approach is to integrate passive components into the board during PCB manufacture. Because they are embedded inside multilayer PCBs, such components are called embedded passives. This work focuses on the materials design, development and processing of polymer-based dielectric nanocomposites for embedded capacitor applications. The methodology of this approach is to combine the advantages of the polymer and the filler to satisfy the electric, dielectric, mechanical, fabrication, and reliability requirements for embedded capacitors. Restrained by poor adhesion and poor thermal stress reliability at high filler loadings, currently polymer-ceramic composites can only achieve a dielectric constant of less than 50. In order to increase the dielectric constant to above 50, effects of high-k polymer matrix, bimodal fillers, and dispersing agent are systematically investigated. Surface functionalization of nanofiller particles and modification of epoxy matrix with a secondary rubberized epoxy to form sea-island structure are proposed to enhance the dielectric constant, adhesion and high-temperature thermal stress reliability of high-k composites. To obtain photodefinable high-k composites, fundamental understanding of the photopolymerization of the novel epoxy-ceramic composite photoresist is addressed. While the properties of high-k composites largely depend on the polymer matrix, the fillers can also drastically affect the material properties. Carbon black- and carbon nanotubes-filled ultrahigh-k polymer composites are investigated as the candidate materials for embedded capacitors. Dielectric composites based on percolation typically show a high dielectric constant, and a high dielectric loss which is not desirable for high frequency applications. To achieve a reproducible low-loss percolative composite, a novel low-cost core-shell particle filled high-k percolative composite is developed. The nanoscale insulating shells allow the electrons in the metallic core to tunnel through it, and thereby the composites exhibit a high dielectric constant as a percolation system; on the other hand, the insulating oxide layer restricts the electron transfer between filler particles, thus leading to a low loss as in a polymer-ceramic system.

The goal of the research in this dissertation is to design and characterize embedded passive components, interconnects, and circuits in inhomogeneous, multi-layer liquid crystalline polymer (LCP) substrates. The attenuation properties of inhomogeneous multi-layer LCP substrates were extracted up to 40 GHz. This is the first result for an inhomogeneous LCP stack-up that has been reported. The characterization results show excellent loss characteristics, much better than FR-4-based technology, and they are similar to LTCC and homogeneous LCP-based technology. A two-port characterization method based on measurements of multiple arrays of vias is proposed. The method overcomes the drawbacks of the one-port and other two-port characterizations. Model-to-hardware correlation was verified using multi-layer model in Agilent ADS and measurement-based via model using arrays of the vias. The resulting correlations show that this method can be readily applied to other vertical interconnect structures besides via structures. Comprehensive characterizations have been conducted for the efficient 3D integration of high-Q passives using a balanced LCP substrate. At two different locations from three different large M-LCP panels, 76 inductors and 16 3D capacitors were designed and measured. The parameters for the measurement-based inductor model were extracted from the measured results. The results validate the large panel process of the M-LCP substrate. To reduce the lateral size, multi-layer 3D capacitors were designed. The designed 3D capacitors with inductors can provide optimized solutions for more efficient RF front-end module integration. In addition, the parameters for the measurement-based capacitor model were extracted. Various RF front-end modules have been designed and implemented using high-Q embedded passive components in inhomogeneous multi-layer LCP substrates. A C-band filter using lumped elements has been designed and measured. The lumped baluns were used to design a double balnced-mixer for 5 GHz WLAN application and a doubly double-balanced mixer for 1.78 GHz CDMA receiver miniaturization. Finally, to overcome the limitations of the lumped component circuits, a 30 GHz gap-coupled band-pass filter in inhomogeneous multi-layer LCP substrates, and the measured results using SOLT and TRL calibrations have been compared to the simulation results.