XRF measurement of residual materials in electronics..pdf

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1、NPLREPORTMAT4XRFMeasurementofResidualMaterialsinElectronicsMartinWickhamandChristopherHuntNOTRESTRICTEDAUGUST2007NPLReportMAT4XRFMeasurementofResidualMaterialsinElectronicsMartinWickhamandChristopherHuntIndustryandInnovationDivisionABSTRACTTheaimofthisstudywastoassess

2、thesuitabilityofusingX-rayfluorescence(XRF)systemsforscreeningelectronicspartsintwoapplications-compliancewithRoHSregulations,andtinwhiskermitigation.FifteenXRFsystemswereevaluatedusingtypicalelectroniccomponentsandassemblies,rangingfromcontaminatedplasticcomponents,t

3、hroughbulksolderalloys,tosolderjointsandsolder-terminatedcomponents.TheresultsindicatethatwhilePIN(semiconductordiode)andSiLidetectorbasedsystemsaresuitableforRoHScompliancemeasurementsinplasticsandsolders,proportionalcounterbasedsystemsarenot.XRFsystemsusingPINorSiLi

4、detectorsgenerallyprovedefficientatdistinguishingbetweennon-compliantcomponents(containingtypically2000+ppmofrestrictedsubstances)andcompliantcomponents(typically<500ppmofrestrictedsubstances).Forlevelsbetween500ppmand2000ppm,theuseofadditionaltechniquesmayberequiredt

5、oprovidediscrimination.ThePINorSiLidetectorsalsoprovedefficientatdistinguishingcompliantandnon-compliantsystemscontaining>1000ppmcadmium.Belowthislevel,however,additionaltechniquesmayagainberequiredtoprovidediscrimination.ThelowerRoHSlimitforcadmiumof100ppmdidresultin

6、anumberoffalsedetectionsforthiselement.ProportionalcounterbasedsystemswerecapableofregisteringthepresenceofRoHS-bannedelementsatlevels>3%e.g.suchasfoundinsomeplastics.Belowthislevel,however,theirabilitytodetectanybannedsubstanceswasquestionable,andtheiruseforsuchappli

7、cationsisnotrecommended.Fortinwhiskermitigationapplications,leadlevelsinexcessof4%arerequiredforsoldersamples.Allthesystemssuccessfullydetectedleadatorabovethislevel,providingthesamplesizewaslargeenoughtofillthemeasurementwindow.Indeed,allsystemsprovedcapableofdetecti

8、ng/measuringleadlevelsabove1%insolder.Itisimportanttorememberthattheuseoftheseinstrumentsforboththeapplicationsstudied(RoHSc