Murata's 0603 HF Chip Coils Cover Wide Inductance Range

Murata’s 0603 HF Chip Coils CoverWide Inductance RangeThe past few years have seen thegrowing popularity of compact,slim mobile phones. High-endhandset models, which are usuallymulti-functional, come with highqualitypicture LCD panels and cameramodules. This has led manufacturers toscale down the sizes of the radio frequency(RF) block, and modules including poweramplifier and voltage-controlled oscillator(VCO).Consequently, the sizes of the high-frequencyinductors used in mobile phonesand modules also need to be scaled downto miniature levels.To meet this demand for ultra-smallhigh-frequency inductors, Murata ManufacturingCo., Ltd. is mass-producing andsupplying the LQP03T film-type 0603-sized (0.6 × 0.3mm) high-frequency chipcoil. This product is one of the smallestin the industry.The company, using its proprietarythick-film micro-processing technology,has designed the LQP03T series to includethese features.Wide Range of Inductance VariationThe LQP03T series offers a fulllineup of products with inductance valuesranging from 0.6 to 10nH. Productswith 0.6 to 3.9nH inductance start massproductioncompatibility in 0.1nH steps.Photo 1: High Q-type chip coil from theLQP03T seriesMeanwhile, products with 3.9 to 10nHinductance values are compatible in E-24 steps.Narrow-Deviation CompatibilityA pattern can be processed with highprecision using the thick-film micro-processingtechnology developed by Murata.The process obtained a narrow-deviationcompatibility (Table 1). For products with0.6 to 3.9nH inductance values, deviationis ±0.1nH, while for products with 4.3 to27nH, deviation is reported as ±3 percent.On the other hand, deviation is usually±0.3nH (~ 5.6nH)/±5 percent (6.8nH ~)for a commercially available representativemonolithic-type high-frequency chipcoil, in which an internal electrode patternis formed and is accumulated on aceramic sheet by screen printing.High Q LevelsThe LQP03T series represents a highfrequencychip coil that is produced on acommercial scale.High Q-Type Chip Coils From theLQP03T SeriesAhigh-frequency chip coil is used forimpedance matching and power line highfrequencychokes in the RF circuit of mobilephones and modules. There is a growingneed for a high-performance, highfrequency chip coil for use in reducingpower consumption as well as in scalingdown the sizes of electronics to miniaturelevels.To satisfy such needs, a chip coil withhigh Q value is produced on a commercialscale.External DimensionsThe external view (Photo 1) and theexternal dimensions (Fig. 1) of the highQ-type chip coil from the LQP03T seriesare the same as those of the existingLQP03T series.Table 1: Comparison of deviation values and product lineupsFig. 1: External dimensions of high Q-typechip coil from the LQP037 seriesAEI September 2005Copyright © 2005 Dempa Publications, Inc.37

Q - f CharacteristicsThe Q – f characteristics of a high Q-type chip coil from the LQP03T seriesare compared with the characteristics ofa representative monolithic-type highfrequencychip coil (Fig. 2) available inthe market.This demonstrates that LQP03T chipcoils can have higher characteristics in theexisting series. The present high Q-typechip coils have characteristics that are 15to 40 percent better.Fig. 2: Comparison of the Q - f characteristics of an LQP037 high Q-type chip coil withthose of a representative monolithic-type high-frequency chip coilRating ListThe rating list of this product (Table 2)includes a narrow-deviation compatibility(±3 percent). In the high Q-type product,the guaranteed Q value (500MHz)can be increased to 13. This value increases20 percent as compared with thepresent series.In the present LQP03T series, a performanceequal to that of multilayer1005-sized (1.0 × 0.5mm) products isobtained for 4.7nH or less. Therefore,a chip coil with inductance ranging from5.6 to 10nH is preferred for commercialscale production. This allows the creationof a lineup of products with highQ value for applications (10nH) requiringhigh Q characteristics for impedancematching.In the future, Murata will aim to achievehigher Q characteristics for products withinductance lower than 5.6nH.Table 2: Rating list of high Q-type chip coil from the LQP03T series38 AEI September 2005Copyright © 2005 Dempa Publications, Inc.

High Q TechnologyThe high Q technology used in thishigh-frequency chip coil has the followingcharacteristics.Use of thick-film micro-processingtechnologyIn the screen-printing used for a monolithicmethod, the electrode cross-sectionbecomes flat. In the thick-film micro-processingtechnology developed by Murata,however, low-loss electrode shape can beformed in a high-frequency band. As a result,high Q characteristics are obtainedwith this product.Optimized electrode thicknessIn a high-frequency band, current densityis concentrated on the surface of anelectrode. Known as the skin effect, thisphenomenon also increases the resistanceof the electrode. Therefore, an electrodewas designed to have an optimum thicknessin consideration of the skin thicknessin the operating frequency band (ofmore than 800 MHz) of a mobile phone.Consequently, high Q characteristics canbe acquired.The skin depth is obtained by the expressionbelow.(f: Frequency, µ: Magnetic permeability,σ: Conductivity)Optimized internal structureAn electromagnetic analysis was performedto optimize the wiring pattern, andmonolithic structure to realize high Q characteristics.(Murata has applied for a patentcovering this technology.)SummaryThe growing consumer demand for compactand multi-function mobile phones hascreated a need for compact and high-performancehigh-frequency chip coil. To meetthis demand, Murata has developed a highQ-type chip coil from the LQP03T seriesthat can be produced on a commercial scale.In the future, as high-density mountingtechnology is adopted by handset manufacturers,and mobile phones with builtinhard disc drives and advanced functionalityare developed, the need for compactand high-performance high-frequencychip coils will grow further.To pave the way for development ofchip coils that are smaller (0402-sized),and with higher performance (narrow deviationand high Q characteristics), Murataplans to develop new improved materials,methods, and design. The companywill propose products that are designedto meet the needs of its customers.About This ArticleThe author of this article is YasuhiroNakata, Assistant Chief, DevelopmentSection III, Product Development Department,EMI Filter Division, ComponentsBusiness Unit of Murata ManufacturingCo., Ltd.AEI September 2005Copyright © 2005 Dempa Publications, Inc.39