That is exactly correct. Nice post, Mike!

-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Mike Fenner
Sent: Friday, May 18, 2012 11:44 AM
To: [log in to unmask]
Subject: Re: [TN] PCB Lead Free with Tin Lead Process

Rex is right, you should not be thinking in terms of leaded and unleaded solder but board finish and solder. These are not helpful terms in this context, and lead-free carries emotive connotations which just confuses.
So restating:
The most likely finish on the board is a tin copper alloy, perhaps a modified Sn/Cu such as Sn100C. These modifications are not relevant in this discussion.
So we can consider that the board is finished with tin. The tin is fused and contains a small amount (0.X %) of copper.
This finish will dissolve into your solder at normal soldering temperatures perfectly well. The fused finish makes it superior to an electroplated or electroless finish in terms of ease of joint formation and storage.
The finish is slightly thicker than a plated finish and will contribute to your pot content, but the effect will be marginal. The pot tin content will be increased slightly, but this arguably could be beneficial as usually in Sn/Pb pots the Sn level depletes in use. The level of Cu in the pot will also increase marginally. Whether this increase will be more than marginal and achieve significance is an "it depends", (on pot size, usage rate and so
on) but you will be able to pick it up in your routine assays.
If the finish is a SAC (unlikely) then the Ag content in your pot will rise also but this will be, at least initially benign. Again you assays will pick this up and you will be able to relate assay to results as normal.




Regards


Mike Fenner

Bonding Services & Products
M: +44 [0] 7810 526 317
T: +44 [0] 1865 522 663
E: [log in to unmask]

 

-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Rex Waygood
Sent: Friday, May 18, 2012 9:32 AM
To: [log in to unmask]
Subject: Re: [TN] PCB Lead Free with Tin Lead Process

 You are soldering to the PCB finish you do not melt it. ( think of ENIG )

 You are soldering to the PCB finish you do not NEED to melt it. ( think of ENIG )

:-)

Rex

Sent by me on my iPhone. 


On 17 May 2012, at 13:09, "Juliano Ribeiro" <[log in to unmask]>
wrote:

> Hi to all,
> 
> Is it possible we use PCB with finishing HASL (Lead Free) in our Tin 
> Lead
Process - Solder Wave?
> We need modify some parameters how the temperature?        
> 
> Thank you a lote
> 
> 
> Juliano Ribeiro
> Coordenador de Produção - Placas Eletrônicas Elo Sistemas Eletrônicos 
> S.A.
> Fone: (51) 2131 2217    Fax: (51) 2131 2200
> Cel: (51) 9356 2844

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