简介:近几年,电子产品朝轻,薄,短,小化迅速发展,印制线路板也随着这股潮流朝向高密度封装方向发展。尤其是积层板总数的增加和导通孔以及连接盘的小径化也日益显著。对于积层线路板而言,用来加工层间连接的盲通孔(BVH)的激光方法取决于导通孔和连接盘径。激光器分为CO2激光和UV-Yag激光两种。导通孔径为60μm以上时,则一般用CO2激光加工。由于铜在CO2激光的波长(9.3μm~10.3μm)领域中的吸收比很低,因此"保形法"(在表面铜箔上,蚀刻出需要的加工孔径(开铜窗),再以激光打掉树脂)成为了现在的主流。然而,由于保形法需要蚀刻开铜窗,因此增加了形成图形的工序,而且导通孔的定位取决于下层的定位标记,容易发生错位。随着积层板层数的增加,导通孔和连接盘的小径化发展,越来越需要提高加工速度和定位精度。因此,同时对铜和树脂进行加工的"直接钻孔法"开始被关注。直接钻孔法是根据格柏数据进行导通孔的定位,因此,即使导通孔/连接盘径越趋小型化,也不会发生错位,是一种能够推进多层化,高密度化的先端技术。本文讲述了以直接钻孔法形成高可靠度导通孔时所需的技术和药品。
简介:TheproblemsofcharacteristicpolynomialassignmentinFomasini-Marchesini(F-M)modelⅡof2-Dsystemsareinvestigated.Thecorrespondingclosed-loopsystemsdescribedbyF-MmodelIIareobtainedviathestatefeedback.Usingthealgebraicgeometrymethod,thecharacteristicpolynomialassignmentinthedosed-loopsystemsisdiscussed.Intermsofthetheoryofalgebraicgeometry,theproblemofcharacteristicpolynomialassignmentistransferredtotheonewhetherarationalmappingisonto.SufficientconditionsforalmostarbitraryassignmentcoefficientsofcharacteristicpolynomialinF-MmodelⅡof2-Dsystemsviastatefeedbackarederived,andtheyareavailableformulti-inputcases.Italsohasbeenshownthatthismethodcanbeappliedtoassignthecharacteristicpolynomialwithoutputfeedback.Thesufficientconditionsforalmostarbitraryassignmentcoefficientsofcharacteristicpolynomialofmulti-input2-DsystemsdescribedbyF-MmodelⅡwithoutputfeedbackareestablished.
简介:ThekeyprobleminunstructuredP2Psystemishowtocontrol'Flood'.Somestudiesfocusonconstructingmoreefficienttopologywhileothersfocusonbetterqueryalgorithms.ThispaperpresentsHICUS(HierarchicalInterest-drivenCommunity-basedUnstructuredSystem)motivatedbyabasicthought-whethertheresourcescorrelatewithtopologydistinguishesstructuredandunstruc-turedP2Pessentially.Byintroducinghierarchical'interest',HICUSorganizesaquasi-structuredtopologythroughapuredistributedway,andprovidesanewplatformforqueryalgorithms.Westudytheprocedureandperformanceoftopologyorganization,andthesimulationsshowthatHICUSformsasmall-worldwhichcansignificantlyimprovetheroutingefficiency.
简介:AnewschemebasedonSOA-MZIforall-optical2Rregenerationisproposed.Thecharacteristicsofgainandswitchingwindowofthisdeviceareinvestigatedindetail.Numericalsimulationresultsindicatethatthenonlineargaincompression,thetimedelaybetweentheinputopticalsignalandthewidthoftheopticalpulseareessentialparametersforagoodperformanceofall-optical2Rregeneration.
简介:ReactiveionetchingcharacteristicsofGaAs,GaSb,InPandInAsusingCl2/Arplasmahavebeeninvestigated,itisthat,etchingratesandetchingprofilesasfunctionsofetchingtime,gasflowratioandRFpower.Etchratesofabove0.45μm/rinand1.2μm/rinhavebeenobtainedinetchingofGaAsandGaSbrespectively,whileveryslowetchrates(<40nm/rin)wereobservedinetchingofIn-containingmaterials,whichwerelinearlyincreasedwiththeappliedRFpower.EtchedsurfaceshaveremainedsmoothoverawiderangeofplasmaconditionsintheetchingofGaAs,InPandInAs,however,werepartlyblackenedinetchingofGaSbduetoaroughappearance.
简介:Theneedforwide-bandclockanddatarecovery(CDR)circuitsisdiscussed.A2Gbpsto12Gbpscontinuous-rateCDRcircuitemployingamulti-modevoltage-controloscillator(VCO),afrequencydetector,andaphasedetector(FD&PD)isdescribed.Anewautomaticfrequencybandselection(FBS)withoutexternalreferenceclockisproposedtoselecttheappropriatemodeandalsosolvetheinstabilityproblemwhenthecircuitispoweringon.Themulti-modeVCOandFD/PDcircuitswhichcanoperateatfull-rateandhalf-ratemodesfacilitateCDRwithsixoperationmodes.TheproposedCDRstructurehasbeenmodeledwithMATLABandthesimulatedresultsvalidateitsfeasibility.