Morgan J. Chen

Design and Development of a Package Using LCP for RF/Microwave MEMS Switches

We present the development of an ultrahigh moisture-resistant enclosure for RF microelectromechanical system (MEMS) switches using liquid-crystal polymer (LCP). A cavity formed in LCP has been laminated, at low temperature, onto a silicon MEMS switch to create a package. The LCP-cap package has an insertion loss of less than 0.2 dB at X-band. E595 outgas tests demonstrate that the LCP material is suitable for constructing reliable packages without interfering with the operation of the MEMS switch. The package also passes Method 1014, MIL-STD-883 gross leak, and fine leak hermeticity tests

Development of Thin-Film Liquid-Crystal-Polymer Surface-Mount Packages for

We present the development of thin-film liquid crystal polymer (LCP) surface mount packages for packaging MMICs in Ka-band. The packages are constructed using multilayer LCP films and can be surface mounted on a printed circuit board. Our experimental results demonstrate that the package feed-through transition including bond wires achieve a return loss of -15 dB at 30 GHz and an insertion loss of less than 1 dB in the Ka-band. With the use of an off-package matching network, we achieve the input return loss of less than ~ -15 dB from 28 GHz to 31 GHz and less than ~ -20 dB from 31 GHz to 36 GHz. The use of LCP enclosure provides the near hermetic capabilities in a compact structure

Ka

In this paper, we present the design and fabrication of ultra-wideband (UWB) baluns embedded in multilayer liquid crystal polymer (LCP) flex. Fabrication techniques are demonstrated for processing these commercially available LCP thin-films by standard PCB equipments. Variations in the LCP thin-film thickness are characterized and compared before and after lamination. Results show good dimensional stability of the material, a critical factor in controlling the line impedances and performance of the balun. Electrical results of these baluns show bandwidths exceeding 3.1-10.6 GHz with less than 1 dB insertion loss, and amplitude and phase imbalance less than 1.2 dB and 2deg, respectively. These baluns are ideal for applications in UWB communication systems specified by the IEEE 802.15.3a standard.

-Band Applications

We present the design and development of an organic package that is compatible with fully released RF microelectromechanical systems (MEMS). The multilayer organic package consists of a liquid-crystal polymer film to provide near hermetic cavities for MEMS. The stack is further built up using organic thin-film polyimide. To demonstrate the organic package, we have designed and implemented a 2-bit true-time delay X-band phase shifter using commercially available microelectromechanical switches. The packaged phase shifter has a measured insertion loss of 2.45 plusmn 0.12 dB/bit at 10 GHz. The worst case phase variation of the phase shifter at 10 GHz is measured to less than 5deg. We have also conducted temperature cycling (-65degC to 150degC) and 85/85 to qualify the packaging structures.

Design and Fabrication of Ultra-Wideband Baluns Embedded in Multilayer Liquid Crystal Polymer Flex

We present the design and development of a multilayer organic module that can integrate microelectromechanical systems (MEMS) into a system-in-a-package (SiP). A cavity formed in liquid crystal polymer (LCP) has been laminated, at low temperature, onto a MEMS silicon switch to create a hermetically sealed package. Multilayer organic dielectrics can be integrated on top of LCP films to form a 3D SiP module. The entire SiP hermetically sealed package has a total insertion loss of ~0.1 dB at X-band. The package also passes Method 1014, MIL-STD-883 gross leak and fine leak hermeticity tests. We have demonstrated a 2-bit RF MEMS TTD (true-time delay) switched line phase shifter in this multilayer organic module. The phase shifter achieves an average insertion loss of 1.8 dB/bit, with less than 3deg phase shift variation

Multilayer Organic Multichip Module Implementing Hybrid Microelectromechanical Systems

We present the development of liquid crystal polymer (LCP) packages and thermal compression sealing processes. We demonstrate the complete process for prototyping, sealing, and assembling a single-chip LCP package at microwave frequencies. Using the thermal compression technique, we achieve a measured fine leak rate of 3.7×10-8 cc-atm/s of a LCP package cavity. We have conducted a series of environmental tests such as temperature cycling and 85°C and 85% humidity. We demonstrated that LCP packages have passed major environmental tests and proved to be a reliable package platform.

Development of Multilayer Organic Modules for Hermetic Packaging of RF MEMS Circuits

In this paper, we present the design and development of two low loss, ultra-wide band, planar Marchand baluns (1). The baluns were implemented in a multi-layered liquid crystal polymer (LCP) flex, and in a LCP film laminated on an organic substrate. The best performing balun achieved a bandwidth exceeding 3.1-10.6 GHz with a less than 0.6 dB insertion loss. The amplitude and phase imbalance was measured to be less than 1.2 dB and 2°. The baluns are highly applicable to ultra-wide band communication systems specified by the IEEE 802.15.3a standard. To the best of our knowledge, this is the first reported multi-octave bandwidth balun capable of being implemented in organic substrates using standard printed circuit technologies.

Reliability of liquid crystal polymer air cavity packaging

In this chapter, we present the design and development of thin-film liquid crystal polymer (LCP) surface mount packages for X, K, and Ka-band applications. The packages are constructed using multi-layer LCP films and are surface mounted on a printed circuit board (PCB). Packages include a typical low pass feedthrough design, as well as a new bandpass feedthrough design. Our experimental results demonstrate that the low pass package feedthrough transition including a PCB launch and bond wires achieve a return loss of better than 20 dB and an insertion loss of less than 0.4 dB around Ka-band. We achieve more than 45 dB measured port-to-port isolation of the package across Ka-band. The leak rate of LCP cavities has been found to be 3.6×10–8 atm-cc/s. Experiments show exceptional reliability results for several reliability tests including temperature cycling and prolonged exposure to humidity of packaged amplifiers. Finally, we demonstrate that our bandpass package feedthrough transition including bond wires achieve a 13 dB or higher return loss and less than 0.5 dB insertion loss across K-band. The package transition offers 0.2 dB insertion loss and > 15 dB return loss across X-band, and operates well across 8–27 GHz.

Development of Microwave Ultra-Wide Band Balun using Liquid Crystal Polymer Flex

This chapter presents the design and development of thin-film LCP surface mount (SMT) package feed-throughs for DC to Ka-band applications. Three types of feed-through design will be introduced, via feed, bandpass feed, and lumped element feed, that interface signals from the outside world to a component inside a package. The packages are constructed using multilayer LCP films and are surface mounted on a printed circuit board (PCB) for use. The utilization of an all-LCP enclosure provides a hermetic environment for microwave and millimetre-wave monolithic integrated circuits (MMICs). In addition, mounting MMICs inside a package cavity allows enhanced thermal dissipation because the metal submounts can make direct contact with the PCB or motherboard ground through solder or epoxy. Applications that require lightweight, hermetic, and low-loss modules, which can be developed using LCP, include, but are not limited to, vehicular-collision-warning short-range radar, radar for ground-moving vehicles, point-to-point communication, ground–satellite communication, intersatellite links, and airborne radar. A phased-array system for ground-vehicle or airborne applications may require thousands of modules in the RF link. If each module, typically cased in ceramic and metal, were replaced with LCP packages, then the total weight of a system could be reduced by more than 66%, because ceramic [1] is three times denser than LCP [2]; this can lead to improvements in fuel efficiency. Section 5.1 shows the design, the modeling, and measurement process of a Ka-band package feed-through using vias. The experimental results demonstrate that a package via feed-through including a PCB signal launch structure and bond wires achieves a return loss of better than 20 dB and an insertion loss of less than 0.4 dB at the Ka-band. The package has a measured port-to-port isolation greater than 45 dB up to 40 GHz. An amplifier packaged inside an LCP SMT package is characterized. The measured data are then compared with a circuit-model simulation of the package feed-through, using the on-wafer data of an amplifier to validate the lumped-circuit model.

Liquid Crystal Polymer for RF and Millimeter-Wave Multi-Layer Hermetic Packages and Modules

It has become increasingly apparent that LCP provides an ideal form, fit, and function for many broadband passive components. Since LCP is available in thicknesses less than 1 mil with low dielectric constant, this enables easy design of varying controlled impedances. Further, LCP’s property of being its own adhesive layer provides for a high layer count in a multilayer stack while simultaneously maintaining high-frequency performance that otherwise would be detuned by poor electrical ply layers. This chapter provides design and development examples of broadband passives that benefit from LCP. In section 6.1 we describe a broadband Marchand balun implemented on multilayer LCP covering 4–20 GHz and in section 6.2 a broadband Wilkinson power divider–combiner operating over 2–18 GHz. Section 6.3 presents a novel hybrid coupler using multilayer LCP to achieve a broadband design within a compact area. Broadband LCP Marchand balun A balun converts differential “balanced” signals into single-ended “unbalanced” signals, and vice versa. Marchand baluns are found in numerous microwave circuit designs owing to their characteristically wide bandwidth, low imbalance, and symmetric balanced ports. To achieve a wide bandwidth ratio, a Marchand balun is realized with multilayered broadside coupled microstrip lines implemented on LCP. A novel twin-thickness thin-film [1] structure has been devised specifically to reduce balun conduction loss without sacrificing operation bandwidth.