DER?
Re read the post and my answer.
I misread the last sentence.
"Is this an issue or will the Sn63 properly bond to the solder on the part
terminations to form an acceptable solder joint?"

So I see what you mean.
So my answer is: No. Yes.

NO it's not an issue. YES it will bond etc

Sorry if that was not clear.

Best Wishes
 
 
 
Mike

-----Original Message-----
From: Brian Ellis [mailto:[log in to unmask]] 
Sent: Friday, June 07, 2013 4:22 PM
To: [log in to unmask]
Cc: [log in to unmask]
Subject: Re: [TN] Soldering to SMD device wth Sn98Bi2.5 leads using Sn63Pb37
solder

Sorry Mike, as the question is ambiguous, so is your answer! Simply, 
IMHO, it is not an issue.

Brian

On 07.06.2013 00:17, Mike Fenner wrote:
> Answer yes.
>
> Melting the object you are joining is welding. Soldering is dissolving.
> When you make solder joints to SN plated/coated surfaces they do not melt
in
> the solder. The plating dissolves rapidly and goes into solution. (The
usual
> analogy is sugar into coffee). The underlying or base metal is now exposed
> to solder but dissolves very slowly.  Naturally we don't wait for that
> process to complete :). So on freezing there is a transitional zone which
is
> neither pure solder nor base metal but a mixture. (usually referred to as
> intermetallic layer)
>
> Sn/2.5Bi can be regarded as a tin plating. The small amount of Bi is added
> to control Tin whisker growth. A smaller amount of lead has the same
affect.
> Ceramic devices have had a tin plate - with the lead - for donkey's years
> without a mention for the most part. Now under Pb-free legislation some
> people need to know what their BoM is and the added content information is
> causing everyone to look into things more closely.
>
> Best Wishes
>
>
>
> Mike
>
> -----Original Message-----
> From: TechNet [mailto:[log in to unmask]] On Behalf Of Gerald Bogert
> Sent: Thursday, June 06, 2013 9:19 PM
> To: [log in to unmask]
> Subject: [TN] Soldering to SMD device wth Sn98Bi2.5 leads using Sn63Pb37
> solder
>
> June 6, 2013
>
>
>
> We have an OM who soldered surface mount Opto-couplers with Sn98/Bi2.5
> leads using Sn63Pb37 solder.  The reflow solder profile used was the
> traditional one for Sn63 solder with a measured peak temperature in the
> range of 209 to 215C.  The actual amount of Bi by weight that wound up
> in the completed solder joint was calculated to be about 0.19%.  Based
> on this, there is no issue with a low temperature alloy forming with the
> combination of Bi and Pb.
>
>
>
> However, since the melting point of the Sn98/Bi2.5 solder is around
> 223-231C, the reflow profile used will not result in melting of the
> solder on the part terminations.  Is this an issue or will the Sn63
> properly bond to the solder on the part terminations to form an
> acceptable solder joint?
>
>
>
> [log in to unmask]
>
>
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