High-Q Embedded Passives on Large Panel Multilayer Liquid Crystalline Polymer-Based Substrate

Abstract

This paper presents high-Q embedded passives on a multilayer liquid crystalline polymer (M-LCP)-based substrate for a low-profile, compact, mixed-signal system integration with high performance. A low loss and a low water absorption are advantages of LCP. It is also lower-cost material than other high-frequency materials such as low-temperature cofired ceramic (LTCC) due to its compatibility to printed wiring board (PWB) process. Low loss characteristics of LCP provide high-Q passives such as inductors, capacitors, and matching networks. Seventy-six inductors and sixteen capacitors were characterized from three different 9 in 12 in multilayer LCP panels. Two different locations from each board were chosen to preliminarily validate the large panel process of the M-LCP substrate. The highest quality factor (Q) of 164 was achieved with 2.55 nH at 5.05 GHz. The inductors range from 1.45 to 23.11 nH and Qs range from 43 to 164. Inductors in various embedded layers were characterized for realization of 3-D integration in multilayer LCP substrate for multiband applications. To remove the parasitics from pads and interconnections, a two-step de-embedding technique was applied. The model-tohardware correlations are presented in this paper. Twelve 3-D capacitors were also designed and characterized, which provide more than double the capacitance of standard capacitors. Low-loss filters and baluns at 5 GHz were simulated and measured using the designed high-Q passives. The designed high-Q embedded passives on M-LCP-based substrates provide a systematic 3-D integration method for achieving low-profile, high-performance, and compact modules.Index Terms-Embedded passives, high-, liquid crystalline polymer (LCP), multilayer, three-dimensional (3-D) integration.

3d Lumped Components and Miniaturized Bandpass Filter in an Ultra-Thin M-LCP for Sop Applications

“…The coefficient of thermal expansion (CTE) of LCP can be engineered between 0 and 40 ppm/ • C [6], which improves its thermal compatibility with wide range of materials including PCBs. The fabrication process of LCP does not involve temperatures above 280 • C. This is very low as compared to (850 ∼ 950) • C which is required for LTCC's fabrication [3]. This low temperature processing facilitates the integration of ICs and other components such as micro-electro mechanical systems.…”

“…3850 is the main substrate and 3908 is used as a bonding film between the two 3850s. The only difference between these substrates is that the melting temperature of the 3850 is 315 • C, while 3908 melts at 280 • C. Unlike the designs in [3], this design is completely adhesive-less. The stackup of the process used in this work is illustrated in Fig.…”

“…High Q inductors are required for bandpass filters and matching networks. Inductors fabricated in LTCC or M-LCP, can have very high Qs [2,3]. Spiral inductors are very popular because they provide inductances in the order of several nHs [11], in compact sizes.…”

“…In [3], an M-LCP based library of lumped components has been presented with good quality factors (Qs). This library, however is fabricated in a relatively thicker stack-up with lossy adhesive which is not desirable as detailed in Section 3.2.…”

Liquid Crystal Polymer (LCP) based antenna for flexible system on package (SoP) applications

“…This organic material is characterized by low moisture permeability, low losses and low dielectric constant (ε r = 2.9), excellent for integration of RF and millimeter wave systems (System on Package or SoP) [5] [6].…”