Hi Arnoud



No worries. Soldering on lead free solder with SnPb works as fine as soldering on Copper or on Nickel. You might have to worry a bit about contamination of your SnPb solder in the wave solder machine with Ag and Cu. 

We investigated the case Dave mentioned and I think that the thermal stress of reballing the area grid arrays has a worse effect on the overall reliability than soldering lead free balls with SnPb.

For those who are interested, we published some results in Materials Transactions Vol. 56, No 7, pp988 to 991. Can be downloaded at http://dx.doi.org/10.2320/matertrans.MI201409



Best regards



Günter





Günter Grossmann

Scientist

Empa

Swiss Federal Laboratories for Materials Science and Technology

Überlandstrasse 129

8600 Dübendorf

Switzerland

Tel +41 58 765  4279

Fax +41 58 765 6954

[log in to unmask]

www.empa.ch



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> -----Ursprüngliche Nachricht-----

> Von: TechNet [mailto:[log in to unmask]] Im Auftrag von David Hillman

> Gesendet: Donnerstag, 23. März 2017 13:16

> An: [log in to unmask]

> Betreff: Re: [TN] [COM] Tin-Lead Assembly of SAC305 PTH Connectors

> 

> Hello Arnaud -  as a general rule, having a lead-free component finish in a

> tin/lead soldering process is not a big deal. Technically, the industry has been

> doing that for years with the use of gold or Pd/Ag surface finishes on

> components. The critical variable is "who" is contributing the most solder

> volume to the solder joint formation. Soldering a PTH connector shouldn't be

> a issue as the primary solder volume contribution is coming from the

> soldering process and not the component surface finish.However, area array

> components such as BGAs or CSPs are the other side of the coin as the solder

> sphere is the primary solder volume contributor thus the reason many

> assemblers take mitigation steps such are reballing to avoid solder joint

> integrity issues. I would not expect you to have an issues with your

> connector solder joint integrity based on the details you listed.

> 

> Dave Hillman

> Rockwell Collins

> [log in to unmask]

> 

> 

> On Thu, Mar 23, 2017 at 4:01 AM, GRIVON Arnaud <

> [log in to unmask]> wrote:

> 

> > Dear TechNetters,

> >

> > I have a coming situation where one PTH connector will be degolded and

> > reterminated using a SAC305 solder dipping process.

> > Should I expect wetting/soldering concerns assuming a Tin-Lead

> > soldering process such as wave or selective wave?

> >

> > I have no experience or knowledge of such configuration and am

> > wondering about possible issues due to short contact times between the

> > SAC305 pin finish and the Tin-Lead solder.

> > Thanks in advance for your inputs.

> > Best regards,

> >

> > Arnaud Grivon

> > PCB/PCBA Technology Expert

> > "Un expert, c'est un homme qui connaît de plus en plus sur de moins en

> > moins de choses"

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> >