SMT工程師應具備的設(shè)計技能

SMT工程師應具備的設(shè)計技能

--如何應用DFM

DFM：Designofmanufacturing

創(chuàng)于70年頭初，在機械行業(yè)用于簡化產(chǎn)品結(jié)構(gòu)和削減加工成本。

1994年SMTA首次提出DFX概念。1995年DFX是表面貼裝國際會議的主題。

DFX：DFM；DFT/D；DFA；DFE；DFF；DFS；DFR

1.設(shè)計對SMT的質(zhì)量的影響

。60%的產(chǎn)品成原來源于早期的設(shè)計

。75%的制造成原來源于設(shè)計

。70-80%的生產(chǎn)缺陷干脆與設(shè)計有關(guān)

設(shè)計不良

o造成大量焊接缺陷

□增加修理及返修工作量，奢侈工時，延誤工期

□增加工藝流程，奢侈材料

o返修可能會損壞元器件和印制板

。返修后影響產(chǎn)品的牢靠性

o造成可制造性差，增加工藝難度，影響設(shè)備利用率，降低生產(chǎn)效率

□嚴峻時重新設(shè)計，導致產(chǎn)品開發(fā)周期長

下面是幾種設(shè)計不良例子

1.IC流向不合適

2.焊盤設(shè)計不合適

采納DFX的好處

1.有利于制程的標準化

2.有利于技術(shù)轉(zhuǎn)移，簡化產(chǎn)品轉(zhuǎn)移流程

3.降低新技術(shù)引進成本，削減測試工藝開發(fā)的浩大費用

4.節(jié)約成本，改善供貨實力

5.迎合PCB/SMT技術(shù)日趨困難的挑戰(zhàn)

2.工藝制造流程與設(shè)計

采納表格形式

DFxChecklist

CfPCNW——

2.1定義工藝流程

2.3定義工藝流程

Comments^DFxGuidelinesRefvrunces(Internal)

ksembty(13)ConsMefpressfitpaste-iohcfc19ProcessFlowl^erarcW及左

toWf.chmgttoSMT

Ehfnmatetheseprocesses|9Pruub，Iiw?vttwHchy

Anynonstandardprocesses19PIULSSFicwIweiach-/

rtKpired?________________

244HandWresuiWWe*Addft^I

7WteAdds/OretesEkcnrnatetheM.

DFMTECHNOLOGY

PTHAssembly

「卜%M!fnb<yptocesimpH%5

Ccmpononta??ndPCBjUMt1

?Holeiii9

memc^rx。.皿detection,cg

.ComponentcWarancet

pjiMe，/，#"，"1foffhw.N

?Hiefrna

p<ErT，?*rftfV-M?rmponwM)J加一

DFxGuideSection:1.9Procc*?FlowHierarchy

Vitorcoveray?:Nont1；--------

_____________PTHAssembly

￥，'：--"

里一象君上

ConsidercompatibilitywiththePCB,component,andgeneral

boarddesign:

?Componenttypesavailable(solderedPTH,pressfit,SMT)

?Othercomponenttypesontheboard

?Componentleadlengths

?Componentleadsizeandshape

?Componentleadpitch

?Componentleadsurfacefinish

?Componenttemperatureresistance

?Componentstandoffs

?PCBsurfacefinish

?PCBthickness

?Finishedholesizeofplatedthroughholes

?Etc

ManualSoldering

MwiimsremanualsolderingandsotderfountainatUchbyselectingcomponents

?nddesigningboardlayoutforhigheryielding,moreautomatedhatch

processes,e.9.autoSMT,pasteinhole,fullorselectivewavesolder,pressfrt

OF*GtHdeSoctkm;1.9ProcessFlowHierarchy

Valarcoverage:flone________

^fOWXOGY

2.2PCB外形

2.4PCB外形

ChecklistHemCofiinientb

BoardOutline

gBoanjSize(2)Checkequipmentcapabtlrty44PdnoUBoardIhidCHmandS

matrix.

8M?：erPandUtilizationOptimizecardsizeUseV汕月o(MwiorParalOpMRwMn

⑴"panelexe°

10BoardOuthneShapeComptexit*Udupa<mlizali(xi58CaidOepat咫心Mon

routing

11CcnwChwnfem(10)All4comersPrewntstxndb9CoinerQiainlvfS

damageDesignednuttomteifeie

withplaccinciitsensors

2.3拼板

ReasonsforPaneling:

-Smallcircuits

.Betterspaceutilizotion

(/ahfitalion

-(hinlineAspectRatio

-Productionvolumebalancing

(doublercjlow)

DFMexample河心由p；，n3

33%Boardsavings

bychangingtho

carddimensions

Bhghtly.Previously

paneiizedas2-up.

2OMQQ1fLC^NOLOGY33

2.4元件

力J2.5元件

D4B-----------------

IH，Gi.iJ.i!((??1>fereIV.Hb(Internal)

ictwekiistttemComments

^Jc^mpon^nt

PUcement

19ProcessFlowHierarchy

29PTHon1skteonlyMo^eto1sideori(y

814SMTWeghtUmrtskxSide2

/刈ComponentParisMingoffatSMTmoveto

topside

Height(24)Checkbottomuideheightkxwd\e812HeightLKnrtations

&ICT.topsidefcxprobe,

AOI,aXray_______________

componentsinMlComponentsonbacksidesutaMe813WaveSolderedSMTComponents

(25)kxfuHwave?

/BottomsidePlacementtimesbalancedforDS811SMTLineBalance

Ime?___

2008/06/1011:18

ComponentHeightLimitations

EquipmentTopBottom

/sMT51mrr?(2")25.4mm(V)

1——------------------

Wave76mm(3")38mm(0150")Prefj

_____________95mm(03751|

)

匠y____30mm(1.2T-~25.1nwn(I-

lAOI(MVP)_25.4mm(1")152mm(6~)

--——二工?I

?1(RTI)51mm(2*)51mm(2)

flCT^762mm(035臼cf]

I______________63binni(2t),)Mu*

1FlyingProbe河）20mm(079)

Rework(AirVac)44mm(1.75)254ii)m(1)

ork(SRT)70mm(272)381111n(15")

,-————一?…

ForXray,thesidewithsurfacemappointsiscons/deredth^"u〃(〃〃""

2008/06/1011:21

TopSide/BottomSidebulaiice

Example:

?Double-sidedlineconfiguration:

?1MVIIFonbackside

?3MVIIF+1MPAontopside

Optimumlop

|BGA/QFP

ft

TfH.CC/TSOP13一

1—1

SOIC/Tani176'而

ja；,)

Discrule13201

Placementyate57seconds

P/acemeofgate:62seconds

(move102di>ctetenlubutton0

=9%higherthanoptimum

mnniryA*rtc*^AXO>i2008/06/1011:23

2.5元件貼裝

2008/06/1012:13

PanelEdgeKeepoutc>-SiftgleinmgAssemblyPanel

5mm(0.197")onconveyededges

2nim(0.080M)

onleading/

tcailingends

Indudesrequirementsforallassembly&testequipment.AppliestoSMT&

pasteinholecomponents,onbothsidesofthePCB,

Ifscore&breakisused(ordepanelization,alargerhoardedgecomponent

11Mpoutmayberequired.Thesizeofthekeepoutdependsonthethicknessof

thePCS.

(C”PO、INIORIINTAIION

BREAKAWAYEDGE

Hrrakav”

CttfJC、

J5mm

pirfrriril

oiknlAtlRn

.

ComponentSpacn

"SMIZ"&$OP

2008/06/1012:16

2^6Holeanaviu

ChecklistItemCommvnUDFAGuitkilhtiisReferences(Internal),

L_HolesaVlas

43T<x*ngHoMs(9)2forICTandforFUJISMT54SingleknageReqiMerr-nU

equipment56MUhImagePuneuatioKeqkjfementsl

44VteinPad(17)Present?WbatsueMa?75Accs乂<ibleandUrac印idbl旨Vm

Locohcfis

45ThermalRdiefs(19)ArethesepresentforsolderedP1H6133IbecnalRelnH

parts?

46PressFitHoleSizeCorrecttderance/nominalsue?NA

<7PIMHole/LandSizeCorrectfofwavesoldeiorpastetn613PinSoktei兇Cun耳urents

bole?

*)WawFixtureAnchoringHolesfar$electiveAxtunng864SehKtiwWa\?Sokksi

1Hcka_______________prmnt?

ToolingHoles

?2holesperImageforICT

?(0.125*)diameter

prvtcrvod

?LocMedASFar口fwrtMpouibk^

c.g.cn<fi?9on?l

?Rcn-symmetficHtoprevent

incorrectboardplacementon

futureEES

?2botesperAssemblyPanelforSMT

?4.0mm(0.157**)diameterpreferred,3.18mm(0.125*')tictuplvxl

?Centreslocatedat5mm(0.197*)fromedgwufAP

<ffdfSrrtJon；5,6MultiImagePanelizationRequirefnenlb

2001^/2f

ToolingHoles

Mlnifnum5.1mm(02000)

conipononlkoepoutfromheM

edgo,botho(PCB

Nonpkitedhole,skntolci.wuo

of40OTSmm/0.000mm

(*0003*70.000°)

I”?GuideS?-?t>on.S4bKigleImugcRr(|4ihiMnrnt>(NoPanrhxAllOH)

VrfhwCM>*rr?i<)r:Coni|H>n<*otkv?*poutvuvcicdm7/nd?門I?

ViaInPad

UMofvia-in-paditnetrecommended,M

theyfrequentlyresultKinsuftkienttoMer

joints.Ifrequtrvd,bltndviM?r?preferred

overconvontionalthroughholeviM.

K/5AariitMtHe?ndUnaccefiUbhjYULocMKim

CAiwcredInvtMiKtertlcfi?ck?.

Dcfienduiyocithuvotdvi

wolumuseivuld^i

bump**credludonthu

backMdc<ifthe(.aidmny

afleetscreeiiingforadjdccnt

finepilchckiviccs.

ACemptstoavoidinsufficientsolder

jointsbyincreasingp<)stescreenedcan

resultinsolderballsorbridging.

DfMn

F

?2.7PCBExternalLayei

IChecklistHemCommonts1HA(illhllI'

t

□IPCBExternalLayers

|49GlobalFtdiicials(8)2tdvcialsrninKniKn,3prcfuuedb4Shigk;hndyjcRecjuifoments

Checkfortrace、&silkscrueuin51MUtiIniger>ancHzationRccMiementy

keqxnjtt)1UGlut1ttJiidvilb

50RMs(PGPDots)(11)Multi-uppanel?Tliennetxj56MultiknagePanetuMsRcqutiements

5IIhnagcf<qec(M,*ks

51LandPatterns0402s,Rpccks(*nepitchpaduCanipufMt1ihixyCitiirtton

width,lowutiMitloflpuds.5c

5?LocalFtducialsPiescfKonUnt*pitch?6911oc"Fldliclahs

5/TracesUnderZeroHotitingoftracesunderpent(eg6!)SM1

StandofVComponents［《packs,dtacreieti)67Hp.JCkb/(*piM-kS

54SoldarThtevet(23)Forwaveaolder,conncctoraaridHhd:，川工hwWHWSokiv，

gluedSO1Cs

口cr。,SurbceMapPokitiror_XrayJrni|x；cUof)8hStjffacoMnpPcwntskxXH.r,

GlobalFiducials

Globalfiduclaharousedbythescreeningandplacementmachinesto

opticallyaligntheAssemblyPanelforpastescroonlngandcomponent

placement.

Min4Oinm(0157")dui

saklemhinkopenlfig.free

of&tlK?<;roen&truces

Min1Drum(0MO')

dianieteicopperpad

NotoLOCAIFiducial*(Com(x>n<FntFHducUH)areoddrosnedIntheComponent

LibraryC-HorinoctionoftheGuldollnosDocument.

UMu

OMHIlli,

(il

SIMKIMNMKappri

Fnmbwlme

I(imbskXKIWppm

rech^cxoGY

LandPatternDesign:Rpacks

Problem:

?Landstoofarapartcausedopens(0.030"vs.0.020")

?fracknjnningunderpartliftscomponentoffthelands

Impact:Defectrateof1990ppm

porcomponent.Onaboardwith

300ofthesecomponents.45%

oftheboardsneededtobe

repairedforRpackdefects.

UfMIlCtfWAOGY

F

LandPatternDesign:GullwingHai

?0.050”

+0.050"

0〃Gu.oe$?a>on:0,9GullwingLeadedComponents

v*x8ehns3T?mt1v“vHtiblawifibeaddedtnfuture.

NoteItbcfWcjHth*0??ttmr

PCBfWMtttim*g—i

compenmatetheCAU?-..uIo

?vnenMon翻6Mticdu?mi

2008/06,

SOLDERTHIE\i：S

J-.Mfttfjt91a

????

I_______

?ruwof

piftx

D=

O0

號B

。

二S=

二W_

一

三

三

二

二

一

一0

二=

L-=0

「

八

一

■

S

~

Em

a-

.HI

lS

JU

o5

sL

H

￡

F2.8SolderMaskGuidelines

DFx0cHmm■Rfrwnc”0nt?mil)]

ComE-ng_________________

junk_..一

63G?nonrfSddcrnigMRvcMorwiti

WlwKIM1BetwoenIneftfcbctoaiwxes,

?

etcSo**omdtMduconpcntnitypesm

(Jh干pr6QomporytKryyGWon

5B5K>?r7^MDP?te—P?*NSMDp?<te“6113BGMCGAUwrilMtamMlMir

i?K

6113BGAJCGALandP^tmiwdScMw

BGAaEgorplugging

M,X

/3VWiPlugs_______________________

1013:16

SolderMask

Spacingviolationbetweenlandandvia.

Notenoughclearanceforasoldermask

web.

Impact:riskofsoldermigratingdown

thevia.causingInsufficientsolder

pints.

Potentialsolutions:

?Moveviafurtherfromland

?Reducesoldermaskopeningtopartiallycover

via(ifnotusedastestpoint)

2008/06/1013:18

F

D

T

JQwckNstItemCommentsin■,..?-!Ii.1N，ii-.ui；!-.

SHkscreenunderputt(egB5SMTP

/Components^scretes)___________

Aroundpeds.Ikhxials.Mas.etc412

510Gkii*

ntabonMaricsPolantyorPin1mark,present62CCMIIJxjoer)tMafjcs

andfegitte?Vis出槍oncebevalboinJiMdiKilcornpuit?4ittypestn

populXed?_____(haptci6Co(ii1.mrt：fittlUuiyCnatton

ReferonceDesigratorvRefDebigrdtofs，'UIHW?I12SilKscrecn

part?RefDasignatonslegiblefor

ch^pfarms?_______

碼8GAS.BcnicnOutline

Outlineoutsideofl^Ap-<^tcrbillBGA/CGASrtkscn-cn

SilkscreenClearance

Example;

SilkscreeninsideBGAland

pattern,tooclosetolands.

Impact:silkscreenmay

encroachontolands,causing

poorsolderjoints.

SilkscreenClearance

Exempts：

Spacingviolationbetween

fiducialandsilkscreen

Impact:thisfiducialcan'tbe

used

Suk?creen&trace

k^pout.minim

4.0mm(0.157”)

2008/06/1013:20

PLCCs

Pin10s

居

IndicatorBt

2.10PCBAttribute

ChecklistCommentsDFxGuidoHnetiRefcronce，rnaI)

PCBAttributes

BoardThickness/Thick?VbcivcsoldefIssues?4APanWBoavdDncknenandSire

Stillness(4)Equpncntcapabilityllun/lavgo

numbero(throughIdeMasneed

slipportatSMT7Reparissues?

NorvstandardPCBDunedR&/ocC?MicrcMa?NA

1eatures(5)______

Surtacefwish(6)Cornpatibiiewithcomponenttypes?49SudaceFinish

CompatiblewthotherSmshes

presentgGoldlittm)?________

4Des蛆

SsckupSymmeby____Syrnmetryofsiackup?一

Ostnbution

CopperSymmetry____Copperbalanceoneach]ayer?92.2Copper

；4TiSddcrMask

-M^klVpet12),(-ff!II'Iii*'h1'…

NA

GfoundPlanes3ormoregroundplanes?knpacls

wave8dderboteMl>ndP巾

repar

2008/06/1013:21

Trougtisolderingdireclioni?L{*/。同

COMPOXENIOH1EMAI'IONXSHUDIRtlHON

WAVE&REbLOWSt>l1”

PrejcZlimitetlftt>1,2^tnmpitih

2008/06/1013:22

F

COMftONENIORIENTATION\SPCHILOW

l>IRECTION