SMT工程师应具备的设计技能

SMT工程师应具备的设计技能

--如何应用DFM

DFM：Designofmanufacturing

创于70年代初，在机械行业用于简化产品结构和减少加工成本。

1994年SMTA首次提出DFX概念。1995年DFX是表面贴装国际会议的主题。

DFX：DFM；DFT/D；DFA；DFE：DFF：DFS；DFR

•DFA:DesignforAssonibly,systemlevelmechanicalKMnnbty力，6♦，

•DFE：DesignforEnvironment,为H嚏保少0A伫设计

•DFF:DesignforFabricationofthePCBVf］为印剜电得收就T嘛S!位梭+

・DFS:DesignforSourcing,i.e.SupplyChain为，潼•妈的&计

•DFR：DesignforReliabiltty.UM,产4可・性及运・安全号方叫

.OFx:DesignforMX*,includesallofthe«boveDFM：山处"

1.设计对SMT的质量的影响

。60%的产品成本来源于早期的设计

»75%的制造成本来源于设计

o70-80%的生产缺陷直接与设计有关

设计不良

。造成大量焊接缺陷

。增加修理及返修工作量，浪费工时，延误工期

o增加工艺流程，浪费材料

。返修可能会损坏元器件和印制板

»返修后影响产品的可靠性

。造成可制造性差，增加工艺难度，影响设备利用率，降低生产效率

。严重时重新设计，导致产品开发周期长

下面是几种设计不良例子

I.IC流向不合适

2.焊盘设计不合适

采用DFX的好处

1.有利于制程的标准化

2.有利于技术转移，简化产品转移流程

3.降低新技术引进成本，减少测试工艺开发的庞大费用

4.节约成本，改善供货能力

5.迎合PCB/SMT技术日趋复杂的挑战

2.工艺制造流程与设计

采用表格形式

2.1定义工艺流程

f

2.3定义工艺流程

CheckupItemmentsDFx

Proc*.Flow

P7HAssembly（13）CcjnsidefpressMpaste-inIetc19ProcessFkw/"erarcW决定

sdttef.changetoSMT巴丹

EhmtnaietheseprocessesI9Prodbi*IluwIherarchy

6NorvstanOardAnynonstandardpfoct^seS1*J»I-A...,!..i，匕1：/

_0cgs（14）required?

7WreAods/DeWesElwnmatethem.T44HandWnusoiWHC

23

N（海”，DFMTE3科。（UGY

PTHAwembly

,,•,，」，I….L1”:一.A

jComponenlB

•Hot*»ize

pco.cteftdocticn.cg

.Componentchwancet

peoeMJrot.山壮formw*

1PC8torncnElwaMecomponents♦1，田mfiHreh«H

j.etc

DFxGuideSection:1.9Proc皿NowHierarchy

V^iorewer49c:Non<i-----------------------------

―“srowawr

F

D^lh-------■——PTHAssembly

a叉f

ConsidercompatibilitywiththePCB,component,andgeneral

boarddesign:

Componenttypesavailable(solderedPTH,pressfitzSMT)

Othercomponenttypesontheboard

Componentleadlengths

Componentleadsizeandshape

Componentleadpitch

Componentleadsurfacefinish

Componenttemperatureresistance

Componentstandoffs

PCBsurfacefinish

PCBthickness

Finishedholesizeofplatedthroughholes

Etc.

ManualSoldering

Hinimtrenwmualsolderingandsolderfountainattachbyselectingcomponents

■nddesigningtxMrdlayoutforhigheryielding,moreautomatedbatch

processes*e.9.autoSMLP^steinhole,fullorselectivewavesolder,pressfH

Examples:

•Fton-reflowableSMIcomponents

•Double-sidedsolderedPTHcomponents

•Secondarysidecomponenttooheavy

•Secondarysidecomponenttootall,8aselectnrewavesoAderbcwil

•FewSMTcomponentsplacedonsecondaryside(toofewforaiMornated

(me)

•Etc.

DFnGuideSection;1.9ProcessFlowHierarchy

coverage：Kone

2.2PCB外形

2.4PCB外形

1

ChecklistHemCommentsDFxGutdeltnesReferencesfntemaf'

BoardOutline

BoardSize(2)Checkequipmentcapabtlrty44PdneUBoardIbicKnessandSue

matnx.

8MasterPandUtilizationOptrmizecardsi/cUseVakx<>(52MasterPandOpumzqon

0)"panelexeM

10BoardOuthneShapeComptexil-0depafmilZdlion58CadDepaixH心tvon

routing

11ComerChamfom(10)AH4conun5PicwntsIKnd59CotnerChamfers

damageDesignednoltointeffuic

wKhptecemont■ensorr

2.3拼板

Reasonsforl,aneling:

-Stitdllcircuit

.Hetterspace〃〃/

(luhrirulion<"八〃

-(InlineAspectRatio

-PnHhicfiiHivolumebalancing

(doublercjlowj

H

DFMexampleMd$(erp.mei

iJ99

33%Boarduvings

bychangingtho

carddimensions

Previously

panelizedas2-up.

(WMTEaaXQGY

2.4元件

ItemmvntsDFxGuidehn,sReferences

］，>UJM«C65ormMWtiQatHjnNA

IneededPadgeometiyconsistent

rr?thcM«Kt-alpan?

MlportswMheMe?VWtoMhte^213ProceiBCornpfdiMrtyRequwement%

QIPtcxBGAi^JtDEClrayi.219Compof»efTlSuppty/Packagmg

rnwtualputstubesow<Formats

h-p」S«gw(•gbeyi).崎

f>||tW［；&wH________

tanBOMRar»c/tfianynon*pRM>uctonpaft^

pi。to”■BUMrv4，5・•gt・i

twaiJ，，___________

Cof*iOwcoriwrt'fig»*』，OIo721

B<Vs—

星）F2.5元件

r-----------------------------

f

Comments______DI,ii.td.'hnGbReferuncosOntcrnal)

/Component

Plicemsnt

29lpTHon1sideonlyMoveto1sideOfHy.19ProcessFlowHierarchy

814SMTWeightLKTHISforSide2

!XiComponontWeightPartsfacingoff阖SMTmoveto

topside

3HCcmponentlieigfrt(24)Checkbottomsideheiglitfurwase812HeightLimitations

&ICT.topsidekxflyingprobe,

AOI.&Xray

I32iSMTcomponentsinMlComponentsonbacksidesuture813WaveSolderedSMTComponents

eesdder(25)forfullwave?

33llopside/BottomsidePlacementtimesbalancedRxDS811SMTUneBalance

__prance___line?

2008/06/1011:18

…w-

CorriponentHeightLimitations

<

EquipmentTopBottom

MT51mm(2")254mm(1")

WaveZbrnin(31)3.8mm(0.150")i

95nun(0375iMax

[Xray30mm(12")254n【n(V),

/AOI(MVP)25.4mm(D1521nm(6")

AO?(RTI)51mm(2")51mm(2”)

ICT762nun(03")Pf3

635IIHII(25)MJA

f「lyingProbe20nini(079)20nnn(UZ9)

Rework(AilVac)44mni(1.75")254mrn(1")

Rework(SRT)70mm(275")3UIHI11(15)

,For)Cray,thesidewithsurfacemappointsisconsideredbuttum>2*

TopSide/BottomSideBdlonce

Example:

•Double-sidedlineconfiguration:

•1MVIIFonbackside

•3MVIIF+1MPAontopside

TopBottomOpUcnuinTopUuttont

BGA/tfP100|BGA/QFPU)

PLCC/TSOP301PLCC八SOP30

1______39

^SOfC/Taot17839SCMC/Taut।

1

DiscrutuI13201O.，

Dscratt1422410।

一-

〔

Placementgate:62secondsPlacenianlgje57seconds

(mov6102disCestubutK>m)

=9%higherthanoptimum

orAIrroMxdit>/1011:23

2.5元件贴装

2008/06/1012:13

FPanelEdgeKeepouij-SifigleniRMieAast-.nblypans

2inm(0.080")

onleading/

tidihngends

Indudesrequirementsforallassembly&testequipment.AppliestoSMI&

pasteinhofecomponents,onbothsidesofthePCB.

COMWMN7ORIENTATION

BREAKAWAYEDGE

Hr”ka“・y

nffjc、

J5mm

picfrifril

oiicnlAfhm

ComponentSpacing

―—

"SMIbMi"&SOP

Id

0.050-

o.o3(r

2008/06/1012:16

1■■■■■■■i

2.6

,

二lljCc—muwttOF*G.*■・■fWe—e・)

UMorPGM«camrxjP1>t8S4S4iicswW«m<SOMW

^GmvcrwrWwpaMficompwi

CMPBCBGAAFrwpartsnorba«BC8G<

blowrw^

CM01ySenderCan?*>yiodvfort*qp^cec*aeix

JamjoegQH39aM

AUtoPIMErcx^hpatstoJUtcmAV?8.2Comf»rw<Mf,■>>ctAutomned।

MacNnesKie>tthat47PIHtxa>4n

FTHdesignrU«i

aAmarese^odfarMhibeta512PCbPjifNixntMnng

26Hoieanuviu

1ChecklistItem

CommontsDFKGuitklirtesRuf^rcm.e%(Internal)；

]Hole»&Vias

43TooimgHofcs(9)2forIC1andforFUJISMT54SinglelinageKequtemenU

equipment56hitagcPunvQahuKequtrementsl

44ViamPad(17)Present?Whatsize*4a?75Acceptdblea；dVm

LocohuiB

45ThermalRdiots(19)Arethosepccser*lofsoMeredP1H6133Ibeii向REB

parts?

45Pre»sFitHoleSueCorrecttoierance/nominalsize?NA

47PTHHole/LandSizeCorreclfcxwaveorpastetn「1MSddmeoComponents

hole?864StshKUwWawSokWij

火aeFixtureAnchoringHol。forselecttwwave6tunng

L_"tatei________________present?

ToolingHoles

FMB1

•2holesperImageforICT

•3-1Bmm(0.125*)diameter

preferred

•LocMedasfarjp^rtaspoatbte.

4Mh8Cfl^QOTMl

•Hon-symmetitoprevent

incorrectb(»rdpiacementon

fixture

•2holesperAssemblyPanelforSMT

•4.0mm(0.157")diameterpreferred,3.18mni(0.125*)•»<<<plc%l

•Centreslocateddt5mm(0.197*)fromedgeufAP

G'""Section:5.6M”ltiInnigrP4inellzationRe(|nif<n>.nt.

ToolingHoles

Minimum5hnrn(02000)

coni[>ononlkoopoutfromhoM

edge,bothofPCB

Nonplatedhole,skntolerance

of«0076imn/0.000mm

(♦0.003”/。000”)

L"<GviJt?Station;54MngloImugcRcquHrmrnt5(NoF\inrhi»iUon)

甲occultkfHHrt("vcicdmchzk»__…，,……

ViaInPad

Dcf>cndhigOHUIUMJUIH，

volumu乂・37ne<tvuklvr

iMini|r^creiiludonthu

backside<>tthesdnu«y

dtlectsciceilingtoradjacunt

tinepilchdevices.

Attemputoavoidinsufficientsolder

rnntsbyincreasingpastescreenedcan

resultinsolderballsorbridging.

0/MJEGMAOCy

2.7PCBExternalLaye.

、In.klr.lIb-mkoiiHiiontbDFxGuithdinesRefurenevs(Interndl)

49Globa*Fidticials(8)2lidvcialsiiM(wrnum,3peMied5・1Smgkjhna»juRequirements

Checkfortracer&stlkscreenin*.),-MultiIni<;ef*andiza!i<xi1<匕中川5生川、

keepout310Globjfiducials

90iRMs(PGPDots)(11)MiHti-uppanel?livenFHAX!HM\56MultiknagePan群"at2nRcqmi9nients

5IIknuytjRqectM.wkb

51LandPatterns0402s.RpacksJoepitchp^d<)(1iijiuryCttjalKX)

vrtdth,lowMtiMKiHIpttits,etc

52Lcx^iFiducialsPieseotonAntspitch?6911ocdhducldhs

53tracesUnderZorofloutingattracesunderpad(og65SM1P.r/*i,A^

StandoffComponentsPp.H.ks,dr,(,I.!(1:.)6/U|Njckt>/Cpjr.k8

54SoKarEMB(23)Forwavesolder.com)cctoi3uridBGdSdcctiiVWuwSohici

fltusd80tCs,

55SurfeiceM叩Powrt^1CMXruyJns(xjcliooHhSiiifiK.oMnpP(MUSkxX-Ruy

GlobalFiducials

Globalfiducialsareusedbythescreeningandplacementmachines(o

opticallyalignAssemblyPanelforpastescreeningandcomponont

placement.

Mm4Ornm(01570dg

soklerrnmikojjenkig.free

ofwIXscreen&traces

MtnIOnim(0040')

duinictcfcopperpatl

NotoLocalFlducIftlH(Compon<rntFiducials)ar。addrottnedInthoComponent

LibraryCnrationsectionottheGuidelino*Document

UM〃C，MXOGV

CANWEHSI

0H05<Illi,0(H)MHIP

»>

1J郎

1651.3、

Slnwi-IH.iHMippnSlKKtUMHMMI

Iondvhiime♦1RIO!i

Ic«iiib)lunc|UUppm

LandPatternDesign:

I±1fI

」]II

1^71fT~~]

III]

FPackageTypeG,

4G*iscriticalforgood0402x40.013"

assemblyyield—--—

0603x40.020"

2QWy2lDIMJEOMMUGYfOI

♦Landstoofarapartcausedopens(0.030”vs.0.020”)

♦Trackrunningunderpartliftscomponentoffthelands

Impact:Defectrateof1990ppm

porcomponent.Onaboardwith

300ofthesecomponents,45%

oftheboardsneededtobe

repairedforRpackdefects.

ufMnoffrotOGr

LandPatternDesign:GullwingParis

n

Mrl

U，L

Z1=L1nom+0.050"

Z2=L2,MJ0.050"

Of*GuQt.9GullwingLeadedComponents

cowyrcurrwtly.y点出a.willba.ddcdinfuture

LandPatternDMiQn；GcAw

■一fi

NoteIt*cnticMftuHOmti

PC8ftHMtthvwWhlvO-

cofnpenwfflIheCAO-，

dimwmlcrhalchannelUIMI1

LocalFiducial

£

・ni瞅i

Mont

Prwfurred

■Ml

mm

Pcefrrrml

In“/ac。cori^tiahiaddtt«iyn*a

rttr»iyuuffinepit<hpuftscao

&haruloc.dhdiicl.ih.

DFMrrCHMDLOGY

・，；"”)“，"〃■”」U/n/ii"〃1/jgmu/y/.w向，〃“p咪

foMtuF

]p!V

•曲

"Mks，”r

SIA51IIILwaaiosd

F

口S

s

s=O

o=

p=L

.

s=D

o=E

p=R

T

H

H-

HE

&V

—E

二QS

3P

TA

ET

NR

F

SOLDER

THIEVES

心，7,

2.8SolderMaskGuidelines

――.I

CommuntiIDFxR"Bnc”

BcQ—incptfch.CUMRVK”.

FI^MDPMB—Pr«*wNSMDpad*

BGAatenbngorpk^ging*?

/06/1013:16

I-

Spacingviolationbetweenlandandvia.

Notenoughclearanceforasoldermask

web.

Impactriskofsoldermigratingdown

thevia.causinginsufficientsolder

joints.

Potentialsolutions:

•Moveviafurtherfromland

•Reducesoldermaskopeningtopaitiallycover

via(ifnotusedastestpoint)

i・-———______,■■—

2008/06/1013:18

I“颂■岫八

iwrrafNMC.•space.<»AHMI

-MTrriteHe.•rvucmprolikm.SMH

joor»?f(J9M"GMJIOGV

2008/06/1013:17

2.9Silkscreen

ICheckNvtlivm(KfllhH.»|L>IH><l<>：；1I...(mb(Hall

|s册serve。

159|2sroSlwdoffSHkscioenunderpart(eg@5SMTP-；

|Componentsdiscretes)

^SlkscreenQearanceAroundpads,Ikkidals.Mas.etc412

「

OnentatKnMaricsPofantyOfPin1maikspresent62Ccxu|x4H,irtOti01itau*.viMailes

andfegitte?VisttieonceSwalsoMK!IMWc5np\42nttyposm

populated?，liaptui6ConuLftHoiy(Sieatton

HeferonceDeitgnMmRefDesigiiatompr巴sent70nde，II.*J.i1.KU.H-I()

pad?RefDesignatooilegitsfa

chipfarms?

BGASiBttcreenOuffineOutlinecxit$K)eo^GAp*nnwIer

匈billB3AzeGASilkscrcen

SilkscreenClearance

Example;

SilkscreeninsideBGAland

pattern,tooclosetolands.

Impact:silkscreenmay

encroachontolands,causing

poorsolderjoints.

SilkscreenClearance

Example：

Spacingviolationbetween

fiducialandsilkscreen

knpact：thisfiducialcan'tbe

used

SUk^craen&trace

kevpout.minimum

4.0mm(0.15T*)diametsr

2008/06/1013:20

OrientationMarkings

✓

PiQdOtt

Rptfcks

PolaniymarkI-]口

11atcathode口口Rn1

indjcdtor

口CZ3(fortMt&

□CZ]口debug)

TantalumCapacitors

一|Clrclonl»o

□I___Iaccvptablc

—

Pin1

indicator

QFPs

0

OOM

Ptcc»

Ptn1

IndicatorE

Ptn1II

OBDOODOindicator

F

童________2.10PCBAttribute

ChecklistUniCommentsDfxGuidoHrw博Rcfcronee*(Irdsmal

PCBAttributes

64BoardThickness/Thick•wavesdderKsu<rs?4Panel/BoaidThcknenandSize

Strfimss(4)EqupnentcapebthtyIhm/large

nvrnbefu(thtoughliotevasneed

supportatSMT?Repairissues?

Non-standardPCBBonedR&/<xC?Micarta?NA

features(5)

66SurfaceFmsh(6)Compatiblewithcompcxienltypes?49SurfaceFtmih

CompatitMcwithotherSntshes

___present(姆;Gotd

4andDes

67SwckupSymmefiy“nwne：ryofstackup?

_,i~-•——g22CoppeiOstnbutton

CopperSynirneu/_CopperbalancB(xieachlay

jayikn4H-SddcfMask

Sok»TypeT^RecommernJLPIni^tead

30rmoregroundpUnes?impacts

adderboleHIand

2008/06/1013:21

Troughsolderingdirection川也/）向

COMPOSEDIOIUEMATIONVSi<、nowDIKEIIION

WAVE&RtH.OWSt>ihlKi.SG

Oirrctiwtt

ofPCH

flow

""J

ortcntuHun