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May 2012

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From:
Mike Fenner <[log in to unmask]>
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Date:
Fri, 18 May 2012 17:44:29 +0100
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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

> http://www.elonet.com.br 
>  "Antes de imprimir pense na sua responsabilidade com o meio ambiente."
>   Adote os 4 R´s (Reduzir, Reutilizar, Repensar e Reciclar)!
> 
> 
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