On Thu, 13 Jun 1996 08:13:18 -0700 joef wrote:

> From: joef <[log in to unmask]>
> Date: Thu, 13 Jun 1996 08:13:18 -0700
> Subject: FAB: LPISM over Reflow Sn/Pb
> To: [log in to unmask]
> 
>      Problem: We phased out our last CFC-degreaser to help patch the 
>               alleged ozone hole.
>      Problem: We phased in Probimer 65M which ostensibly has slightly lower 
>               adhesion than Probimer 52.
>      Problem: curtain-coated S/M peeling from reflowed tin/lead 
>      
>      Our standard surface prep for SMOBC is pumice (no brushes) but pumice 
>      dulls the reflow finish and has been rejected by the customer for 
>      aesthetics in the past.  Customer is high-rel avionics and will likely 
>      be a bit stubborn with design change recommendations.
>      Does anyone have a successful pre-clean method for S/M over reflow?
>      
>      a conveyorized solder brite?
>      a non-CFC degreaser?
>      a solvent?
>      
>      Thanks in advance.
>      Joe Felts
>      PC World, Toronto
> 
									
									
	Joe: Could you supply a little more information?		
	     What is it you are tying to clean/remove?			
	     Is it oxides,is it fusing fluid residues on the Sn/Pb or are you 
trying to create a higher surface energy(rougher)to bond to?		
	     When/where is it peeling,at your bare board level or assembly?	
	      Is it peeling on large ground planes,all Sn/Pb cicuits or on 
everything?								
	     What type of adhesion test are you doing,tape?		
	     Quite a bit of our LPI work is done on fused Sn/Pb and we have 
not had any adhesion problems.						
	     Depending on what you're trying to accomplish there are some 
things that can be done for surface modification and LPI bake/cure cycles to 
improve adhesion.Call me if you would like (206)356-6076.		
									
						Regards   		
						Michael Barmuta		
						Staff Engineer		
						Fluke Corp.		
						Everett Wa.