Low cost fabrication processing for microwave and millimetre-wave passive components

Microwave and millimetre-wave technology has enabled many commercial applications to play a key role in the development of wireless communication. When dissipative attenuation is a critical factor, metal-pipe waveguides are essential in the development of microwave and millimetre-wave systems. However, their cost and weight may represent a limitation for their application. In the first part of this work two 3D printing technologies and electroless plating were employed to fabricate metal pipe rectangular waveguides in X and W-band. The performance for the fabricated waveguides was comparable to the one of commercially available equivalents, showing good impedance matching and low attenuation losses. Using these technologies, a high-performance inductive iris filter in W-band and a dielectric flap phase shifter in X-band were fabricated. Eventually the design and fabrication of a phased antenna array is reported. For microwave and millimetre-wave applications, system-on-substrate technology can be considered a very valuable alternative, where bulky coax and waveguide interconnects are replaced by low-loss transmission lines embedded into a multilayer substrate, which can include a wide range of components and subsystems. In the second part of this work the integration of RF MEMS with LTCC fabrication process is investigated. Three approaches to the manufacture of suspended structures were considered, based on laser micromachining, laser bending of aluminium foil and hybrid thick/thin film technology. Although the fabrication process posed many challenges, resulting in very poor yield, two of the solution investigated showed potential for the fabrication of low-cost RF MEMS fully integrated in LTCC technology. With the experience gained with laser machining, the rapid prototyping of high aspect ratio beams for silicon MEMS was also investigated. In the third part of this work, a statistical study based on the Taguchi design of experiment and analysis of variance was undertaken. The results show a performance comparable with standard cleanroom processing, but at a fraction of the processing costs and greater design flexibility, due to the lack of need for masks.Open Acces

Advances in panel glass packaging of mems and sensors for low stress and near hermetic reliability

MEMS based sensing is gaining widespread adoption in consumer electronics as well as the next generation Internet of Things (IoT) market. Such applications serve as primary drivers towards miniaturization for increased component density, multi-chip integration, lower cost and better reliability. Traditional approaches like System-on-Chip (SoC) and System on Board (SoB) are not ideal to address these challenges and there is a need to find solutions at package level, through heterogeneous package integration (HPI). However, existing MEMS packaging techniques like laminate/ceramic substrate packaging and silicon wafer level packaging face challenges like standardization, heterogeneous package integration and form factor miniaturization. Besides, application specific packages take up the largest fraction of the total manufacturing cost. Therefore, advanced packaging of MEMS sensors for HPI plays a critical role in the short and long run towards the SOP vision. This dissertation demonstrates a low stress, reliable, near-hermetic ultra-thin glass cavity MEMS packages as a solution that combines the advantages of LTCC/laminate substrates and silicon wafer level packaging while also addressing their limitations. These glass based cavity packages can be scaled down to 2x smaller form factors (<500μm) and are fabricated out of large panel fabrication processes thereby addressing the cost and form factor requirements of MEMS packaging. Flexible cavity design, advances in through-glass via technologies and dimensional stability of thin glass also enable die stacking and 3D assembly for sensor-processor integration towards sensor fusion. The following building block technologies were explored: (a) reliable cavity formation in thin glass panels (b) low stress glass-glass bonding, and (c) high throughput, fully filled through-package-via metallization in glass. Three main technical challenges were overcome to realize the objectives: (a) glass cracking, side wall taper, side wall roughness and defects, (b) interfacial voids at glass-polymer-glass interface and (c) electrical opens and high frequency performance of copper paste filled through-package-vias in glass.M.S

PIXAPP Photonics Packaging Pilot Line development of a silicon photonic optical transceiver with pluggable fiber connectivity

This paper demonstrates how the PIXAPP Photonics Packaging Pilot Line uses its extensive packaging capabilities across its European partner network to design and assemble a highly integrated silicon photonic-based optical transceiver. The processes used are based on PIXAPP's open access packaging design rules or Assembly Design Kit (ADK). The transceiver was designed to have the Tx and Rx elements integrated on to a single silicon photonic chip, together with flipchip control electronics, hybrid laser and micro-optics. The transceiver used the on-chip micro-optics to enable a pluggable fiber connection, avoiding the need to bond optical fibers directly to the photonic chip. Finally, the packaged transceiver module was tested, showing 56 Gb/s loop-back modulation and de-modulation, validating both the transmitter and receiver performance

Enabling Solutions for Integration and Interconnectivity in Millimeter-wave and Terahertz Systems

Recently, Terahertz (THz) systems have witnessed increasing attention due to the continuous need for high data rate transmission which is mainly driven by next-generation telecommunication and imaging systems. In that regard, the THz range emerged as a potential domain suitable for realizing such systems by providing a wide bandwidth capable of achieving and meeting the market requirements. However, the realization of such systems faces many challenges, one of which is interconnectivity and high level of integration. Conventional packaging techniques would not be suitable from performance perspective above 100 GHz and new approaches need to be developed. This thesis proposes and demonstrates several approaches to implement interconnects that operate above 100 GHz. One of the most attractive techniques discussed in this work is to implement on-chip coupling structures and insert the monolithic microwave integrated circuit (MMIC) directly into a waveguide (WG). Such approach provides high level of integration and eliminates the need of galvanic contacts; however, it suffers from a major drawback which isthe propagation of parasitic modes in the circuit cavity if the MMIC is large enough to allow such modes to propagate. To mitigate this problem, this work suggests and investigates the use of electromagnetic bandgap (EBG) structures that suppresses those modes such as bed of nails and mushroom-type EBG structures. The proposed techniques are used to implement several on-chip packaging solutions that have an insertion loss as low as 0.6 dB at D-band (110-170 GHz). Moreover, the solutions are demonstrated in several active systems using various commercial MMIC technologies. The thesis also investigates the possibility of utilizing the commercially available packaging technologies such as Embedded Wafer Level Ball Grid Array (eWLB) packaging. Such technology has been widely used for integrated circuits operating below 100 GHz but was not attempted in the THz range before. This work attempts to push the limits of the technology and proposes novel solutions based on coupling structures implemented in the technology’s redistribution layers. The proposed solutions achieve reasonable performance at D-band that are suitable for low-cost mass production while allowing heterogeneous integration with other technologies as well. This work addresses integration challenges facing systems operating in the THz range and proposes high-performance interconnectivity solutions demonstrated in a wide range of commercial technologies and hence enables such systems to reach their full potential and meet the increasing market demands

Mesoscale Ceramic Cylindrical Ion Trap Mass Analyzers For In Situ Sample Analysis

As wireless network devices and IOT connectivity develop, the application and demand for small, low power, in situ sensors and instruments will expand. There are continuous efforts in the miniaturization of sensors and scientific instrument systems for conventional to field deployable and rugged hand held units for personal use to extreme harsh environment applications. This work investigates mesoscale cylindrical ion trap (CIT) mass analyzer design and the benefits of CITs realized via additive manufactured metalized ceramic material systems for improved ion signal, low power performance, and extended dynamic range. Rugged monolithic miniature mass spectrometer ceramic CIT chips have been produced that have increased signal output with reduced power consumption. We have demonstrated via simulation and experiment ~80% and greater CIT ion detection efficiency, signal improvement of the percentage of analyzed ions detected, from 50% detection for conventional CIT designs. Utilizing a unique notched ring electrode design that increases the ion signal output to the detector, the electron ionization quantity and power required for mass spectrum generation and tuning was reduced by ~1 watt or 33%, as well as the required gain of the ion detector. Increased CIT ion detection efficiency effectively increases the total amount of the sample analyzed versus what is lost, thus increasing the instrument sensitivity and data collected, reducing duty cycle and power. Identical CITs of a ring electrode radius, ro = 1 mm, were fabricated from low temperature co-fired ceramic (LTCC) and the stainless steel (SS) for performance comparison and were tested in mass instability scanning and resonance ejection modes to produce Perfluorotribuytlamine (PFTBA) mass spectra. The ceramic material system offers design anFd material benefits which reduce the CIT power consumption by 29x from ~10.20 mW power consumption of the stainless steel CIT design to 0.36 mW for the ceramic CIT, as well as enabling batch fabrication, reduced cost and manufacturing defects. While the stated design and material system benefits may facilitate CIT and MS system miniaturization, and the production of the ceramic CIT chip, the proof of concept of CIT ion ejection efficiency via the notched ring electrode may enhance ion trap designs at any scale

Development in Electronic Packaging – Moving to 3D System Configuration

The electronic industry is reducing package dimensions of components as well as complete electronics systems. Surface mount device passives and semiconductor chips have to be mounted together bringing a functional system that must realize the required function with necessary reliability and acceptable price. To make up a reliable and cost effective system, the size and weight is being reduced by employing lower voltages and higher speeds. For example, the typical size of SMD passives 30 years ago was 1206 when they were first introduced. Generally, all components including electrical joints are becoming miniaturized and smaller. The industry is moving toward a reduced size of 0201 and 01005 for passives, new fine pitch packages for actives, but the PCB now feature limits for further integration. System on Package (SOP) is one way to reach the three-dimensional package concept where components will be placed in three-dimensional configuration. A similar concepts are “Package on Package” (PoP) or ”Package in Package” (PiP)

Designing antennas and RF components for upper millimeter frequencies using advanced substrate technology

Abstract. When shifting towards high frequency range, integration in the RF-front end becomes crucial. The ongoing planning of 6G communications systems causes a need to explore the possibilities beyond current 5G systems. To address the compactness and smaller sizes of the RF circuit components, the Integrated Passive Devices (IPD) multilayer technology provides us one solution to this problem. There are options already being tested in terms of implementing on-chip components, especially Antenna-in-Package (AiP) designs with a variety of different substrates. Among these technologies, Low Temperature Co-Fired Ceramic (LTCC) can be seen as a choice offering the freedom of multiple metal layers. IPD can be used for providing AiP solutions, as well as passive components such as baluns, filters, and power dividers. The main target of this thesis is to explore the possibilities and limitations for high frequency designs offered by IPD technology developed by (VTT) Technical Research Centre of Finland. The technology has already been tested at 20 GHz, but the focus was to reach the D-band (110–170 GHz) frequency range and subsequently up to even G-band (220–330 GHz). The technology utilizes 3 metal layers and a high resistivity silicon substrate (a lossy material). Starting off with simple transmission line structures (microstrip lines, strip lines and coplanar waveguides), the designs up to 330 GHz, provided information on the possibilities offered by this technology. After that, different AiP options were simulated with frequencies ranging from D- band to G- band. In addition to single elements, also antenna arrays were studied. Additionally, bandpass filters were designed. The dielectric thickness and the width and thickness of 3 the metal layers play a pivotal role in defining the performance of all the RF components designed using this technology. Furthermore, the size and pitch of the RF probe pads used to excite the structures show an impact on the overall behavior of the transmission lines.Antennien ja RF-komponenttien suunnittelu ylemmille millimetritaajuuksille edistynyttä substraattitekniikkaa käyttäen. Tiivistelmä. Siirryttäessä korkeammille taajuuskaistoille RF-etupään integrointi on entistä tärkeämpää. Käynnissä oleva kuudennen sukupolven (6G) viestintäjärjestelmien suunnittelu edellyttää nykyisiä 5G-järjestelmiä edistyksellisempien teknologisten mahdollisuuksien tarkastelua. Entistä pienempien RF-piirikomponenttien toteuttaminen vaatii uusia teknisiä ratkaisuja, ja yksi mahdollisuus komponenttien pienentämiseen on käyttää integroituihin passiivirakenteisiin (Integrated Passive Devices, IPD) pohjautuvaa monikerrosteknologiaa. Eri vaihtoehtoja on jo testattu sirulle sijoitettavien komponenttien toteuttamiseen eri substraattimateriaaleilla, etenkin paketoitujen antenniratkaisujen (Antenna-in-Package, AiP) suunnittelemiseksi. Eräs vaihtoehto IPD:lle on matalan lämpötilan yhteissintrattava keraamiteknologia (Low Temperature Co-Fired Ceramic, LTCC), joka mahdollistaa useamman metallikerroksen hyödyntämisen suunniteltaessa AiP-rakenteita sekä muita passiivikomponentteja (kuten symmetrointimuuntajia, suodattimia sekä tehonjakajia). Tämän opinnäytetyön päätavoitteena on tarkastella Valtion teknillisen tutkimuskeskuksen (VTT:n) kehittämän IPD-teknologian mahdollisuuksia ja rajoitteita korkean taajuuden rakenteiden suunnitteluun. IPD-teknologiaa on tähän mennessä testattu 20 GHz:n taajuudelle asti, mutta tässä työssä tarkoituksena on tutkia teknologiaa 110–170 GHz:n taajuuksille (D-kaista) sekä myöhemmin aina 220–330 GHz:iin saakka (G-kaista). Teknologia hyödyntää kolmea metallikerrosta sekä häviöllistä korkean ominaisvastuksen piisubstraattia. Yksinkertaisten siirtojohtorakenteiden (mikroliuskajohto, liuskajohto, koplanaarijohto) suunnittelu aina 330 GHz:n taajuudelle asti antoi tietoa teknologian mahdollisuuksista, minkä jälkeen erilaisia AiP-rakenteita simuloitiin D- ja G-kaistoilla. Yksittäisten antennielementtien ohella tarkasteltiin antenniryhmiä. Työssä suunniteltiin myös kaistanpäästösuodattimia. Käytettävissä olevien metalli- ja substraattikerrosten paksuudella sekä niiden mahdollistamilla liuskanleveyksillä on keskeinen rooli IPD-teknologialla suunniteltujen komponenttien suorituskyvyn kannalta. Lisäksi RF-mittapäiden kontaktikohtien koko ja välimatka vaikuttavat siirtojohtojen ominaisuuksiin

HIGH PERFORMANCE PIEZOELECTRIC MATERIALS AND DEVICES FOR MULTILAYER LOW TEMPERATURE CO-FIRED CERAMIC BASED MICROFLUIDIC SYSTEMS

The incorporation of active piezoelectric elements and fluidic components into micro-electromechanical systems (MEMS) is of great interest for the development of sensors, actuators, and integrated systems used in microfluidics. Low temperature cofired ceramics (LTCC), widely used as electronic packaging materials, offer the possibility of manufacturing highly integrated microfluidic systems with complex 3-D features and various co-firable functional materials in a multilayer module. It would be desirable to integrate high performance lead zirconate titanate (PZT) based ceramics into LTCC-based MEMS using modern thick film and 3-D packaging technologies. The challenges for fabricating functional LTCC/PZT devices are: 1) formulating piezoelectric compositions which have similar sintering conditions to LTCC materials; 2) reducing elemental inter-diffusion between the LTCC package and PZT materials in co-firing process; and 3) developing active piezoelectric layers with desirable electric properties. The goal of present work was to develop low temperature fired PZT-based materials and compatible processing methods which enable integration of piezoelectric elements with LTCC materials and production of high performance integrated multilayer devices for microfluidics. First, the low temperature sintering behavior of piezoelectric ceramics in the solid solution of Pb(Zr0.53,Ti0.47)O3-Sr(K0.25, Nb0.75)O3 (PZT-SKN) with sintering aids has been investigated. 1 wt% LiBiO2 + 1 wt% CuO fluxed PZT-SKN ceramics sintered at 900oC for 1 h exhibited desirable piezoelectric and dielectric properties with a reduction of sintering temperature by 350oC. Next, the fluxed PZT-SKN tapes were successfully laminated and co-fired with LTCC materials to build the hybrid multilayer structures. HL2000/PZT-SKN multilayer ceramics co-fired at 900oC for 0.5 h exhibited the optimal properties with high field d33 piezoelectric coefficient of 356 pm/V. A potential application of the developed LTCC/PZT-SKN multilayer ceramics as a microbalance was demonstrated. The final research focus was the fabrication of an HL2000/PZT-SKN multilayer piezoelectric micropump and the characterization of pumping performance. The measured maximum flow rate and backpressure were 450 μl/min and 1.4 kPa respectively. Use of different microchannel geometries has been studied to improve the pumping performance. It is believed that the high performance multilayer piezoelectric devices implemented in this work will enable the development of highly integrated LTCC-based microfluidic systems for many future applications