1.0ScopeThismethodprovidesatechniquefordetermin-
ingtheoverallthicknessoftreatedoruntreatedcopperfoils
andfordeterminingtheprofilefactoronfoilsusedforthe
manufactureofelectricalgradelaminatesandmultilayercircuit
boards.
Theprofilefactoristhedifferencebetweentheactual
mechanicalthicknessofthefoilandthecalculatedeffective
thicknessbasedontheweightanddensity.Thismethodwill
definetheprofilefactortoabout0.00025mm[0.01mil],how-
ever,duetovariationswithinthefoiltheuseofvaluesofincre-
mentslessthan0.00125mm[0.05mil]isseldomnecessary
ontreatedfoils.Thismethodeasilyachievesthislevelofpre-
cision.
A.Background:Whileforasamplewithperfectlyflatsur-
facesthetheoreticalandactualthicknesswouldbeequal,
inpracticevirtuallyallfoilsusedinsuchapplicationsare
manufacturedwithoneroughsurfacetoenhanceadhe-
siontothesubstrate.Sincethisirregularsurfacereduces
theeffectiveelectricalthicknessofthesubstratematerial
andmayaffectotherelectricalandmechanicalproperties,
itisoftenusefultoquantifythedegreeofvariationfromthe
theoreticalthickness.Thetechniquedescribedhereinpro-
videsameasureofthisvariation,whichonnormalfoil
generallyrunsfrom0.0025to0.025mm[0.1milto1mil]
andmayrepresentovera50%increasetothefoilstheo-
reticalthickness.
B.Applications:Theeffectiveminimumelectricalthicknessof
adouble-sidedlaminatemaybereadilydeterminedby
subtractingtheoverallmechanicalthicknessofthefoil
(bothsides)fromtheoverallthicknessofthelaminateata
particularlocation.
Theactualmechanicalthicknessofthebasematerialmay
beestimatedbysubtractingtheeffectivethicknessofthe
copperfoilfromtheoverallmechanicallaminatethickness.
TheProfileFactormaybeusedtomonitorvariationsof
incomingfoilsofaparticulartypewithouttimeconsuming
microsectioning.Comparisonofdifferentfoiltypesmaybe
madebutjudgmentorperformanceshouldbemade
usingtheactualcriteriaofinterest.
2.0ApplicableDocumentsNone.
3.0Apparatus
3.1Papercutter
3.225.4mm[1inch]precisioncutter,324mm[12inches]
longminimum.
3.3Analyticalbalance1mg.resolution.
3.4Standard25.4mm[1inch]ratchetmicrometerwith
0.0025mm[0.0001inch]resolution(orbetter),25psipres-
sure,6.4mm[0.25inch]anvil.
3.5Paralleljawpliers.
4.0Specimen
4.1Number:3.
4.2Form:324x25.4mm[12.00x1.00inches].
4.3Location
4.3.1Roll:Specimensshallcutacrossthewidthofthefoil
fromthecenterandbothedgesoftheroll.
5.0Procedure
5.1Test
5.1.1Foldthespecimenarounditselfintoa10ply25.4mm
[1inch]longsamplemaintainingthetreatedsideoutsothat
therearenotreatedsidetotreatedsideinterfaces.
5.1.2Weighthespecimenontheanalyticalbalancetothe
nearest0.001gramandrecordasWI.
5.1.3Compresstheouter3.2mm[1/8inch]ofthespeci-
menusingapairofplierswithparalleljawsorequivalent
device.
5.1.4Usingthemicrometer,measurethethicknessofthe
specimentothenearest0.0025mm[0.0001inch]orbetterin
fourlocationsaroundthecenteratleast3.2mm[1/8inch]
fromthecompressededges.Usethreeclicksofaproperly
calibratedratchetmicrometer(providingaforceof25psi±5
psionthesample).
TheInstituteforInterconnectingandPackagingElectronicCircuits
2215SandersRoad?Northbrook,IL60062
IPC-TM-650
TESTMETHODSMANUAL
Number
2.2.12.1
Subject
OverallThicknessandProfileFactorofCopper
FoilsTreatedandUntreated
Date
9/87
Revision
OriginatingTaskGroup
N/A
MaterialinthisTestMethodsManualwasvoluntarilyestablishedbyTechnicalCommitteesoftheIPC.Thismaterialisadvisoryonly
anditsuseoradaptationisentirelyvoluntary.IPCdisclaimsallliabilityofanykindastotheuse,application,oradaptationofthis
material.Usersarealsowhollyresponsibleforprotectingthemselvesagainstallclaimsorliabilitiesforpatentinfringement.
EquipmentreferencedisfortheconvenienceoftheuseranddoesnotimplyendorsementbytheIPC.
Page1of2
5.2Calculation
5.2.1Calculatetheeffectivethicknessofthefoilinmilsby
multiplyingtheweightofthe324x25.4mm[12x1inch]
specimenby0.572mil/g.
Te(mil)=0.572
mil
g
xW(g)
Te=ThicknessEquivalent
Samplecalculation:
W=2.16g
Te=0.572mil/gx2.16g=0.0031[1.236mil]
5.2.2Calculatetheaveragemechanicalthicknessmicrome-
terofeach10plyspecimenfromthefourvaluestakenon
eachsample.
5.2.3Calculatetheaverageoverallthickness(Tm)foreach
samplebydividingtheaveragethicknessofthespecimenby
thenumberofplies.
5.2.4Calculatetheaverageprofilefactorofthefoilforeach
specimenbysubtractingtheeffectivethicknessfromtheaver-
agemechanicalthickness.
PF=Tm?Te
5.2.5Averagethethreevaluesofprofilefactor.
5.3Report
5.3.1Reporttheaverageprofilefactorforthethreespeci-
menstested.
5.3.2Reporttheaveragemechanicalthicknessforthethree
specimenstested.
6.0Notes
ThicknessofSpecimen:Thethicknessofthespecimenused
mustbeatleast100timestheprecisionofthethickness
measuringdevice.Morepliesmayberequiredforlighterfoil,
e.g.0.5ouncepersquarefootfoilifthemicrometerprecision
is0.0025mm[0.0001inch]sinceaminimumof0.25mm[10
mils]isrequiredtofulfillthe1%requirement.Ifaprecision
25.4mm[1inch]cutterisnotavailableapapercutteror
punchanddiesetmaybeusedforsamplepreparation,how-
ever,theareasofthesampleusedforweightdetermination
mustbeknownto1%orbetterandthethicknesssample
mustbefreefromwrinklesorcreases.
Precision:Astudyofvarious1oz./ftcopperfoilsresultedin
reproducibilitybetweentestersusingahandmicrometerwith
0.0013mm[0.00005inch]resolution.
ComparisontoOtherMethods:Theprofilefactordetermined
bythistestmayvaryslightlyfromtheactualprofileheightas
estimatedfromothermethods,suchasmicrosectioningor
profilometery.Thedenserthetreatmentstructurethemore
thistechniquewillunderestimatethetrueprofileheight.The
precisionofthismethodbetweentesterswasabout50%bet-
terthanmicrosectioningindeterminingtheamountofprofile
onlowprofiletreatedEDcopperusingthesamenumberof
determinationsusingasinglemicrosectionasthetestvehicle.
Thetimerequiredbythismethodisunder5minutes.
Thickness
Mean
(mils)Microns
Standard
Deviation
(mils)Microns
Profile
Factor
Mean
(mils)Microns
Standard
Deviation
(mils)Microns
TreatedEDFoilClass1
1oz.ft
2
1.6140.90.0150.380.3508.890.0150.38
TreatedEDFoilClass3
1oz./ft
2
1.6241.20.0130.330.2516.380.0130.33
UntreatedRAFoilClass7
3/4oz./ft
2
1.0626.40.0100.250.0611.550.0110.28
IPC-TM-650
Number
2.2.12.1
Subject
OverallThicknessandProfileFactorofCopperFoilsTreatedand
Untreated
Date
9/87
Revision
Page2of2
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