Carol,

the readings of the XRF machines are very dependent on how you define the application and whether you do or don't do a calibration using pure elements. It seems that you can also improve reading accuracy by having standards of thicknesses close to the layers you analyze.

I would suggest getting the manufacturer of your machine involved.

Good luck,
        Ioan

>   -----Original Message-----
>   From: Leadfree [mailto:[log in to unmask]] On Behalf Of Carol Spiers
>   Sent: Friday, January 27, 2006 1:20 PM
>   To: [log in to unmask]<mailto:[log in to unmask]>
>   Subject: [LF]
> 
>   I have just had an analysis completed on a first batch run of leadfree
>   boards.  Results indicate we have  uniform contamination of 0.14-0.19
>   layer of lead across the board.  The testing and measurements were
>   obtained using  xray flouresence and indicate the lead is on the top
>   layer of the melded solder.  We confirmed that all parts were documented
>   as being Lead Free (but not tested by us for compliance).  Boards were
>   double sided silver immersion smt and thru hole combinations.  Solder
>   paste used was SAC, wave solder bar used was SAC.  The wave solder
>   machine is brand new (never used in a leaded process).  SMT oven is used
>   for both leaded and unleaded processes. 
>   Because the contamination appears to be uniformly spread across the
>   board I tend to think this isn't a problem related to a couple of
>   components not actually being lead free and contiminating the huge pot
>   of solder in the wave.  One suggestion was that there might have been a
>   thin layer of lead over top of the silver immersion on the bare boards.
>     
>   Is there anyone out there that would care to offer some suggestions as
>   to where we should focus our investigation or if any alternative testing
>   should be used. 
>   So far we are going to:
>   1) do comparison testing of two batches of bare boards of the same
>   product coming from different suppliers and undergoing identical
>   processing.  
>   2) have a sample of the wave solder evaluated for contaminates and to
>   establish the bench for future sample evaluations. 
> 
>   Once again, your input and help will be much appreciated. 
> 
>   Carol
>   C. M. Spiers
>   Director of Operations
>   Interalia Inc. 
> 
> 
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