I echo both Dave and Andy's comments.  In the 1994-1997 National Center for Manufacturing Sciences Pb-Free Project there was a lot of evaluation of tin-bismuth solders.  When the program ended in 1997 the general feeling was that tin-bismuth solders probably won't play a significant part in Pb-Free soldering.  One of the major concerns back then was the possibility of lead (Pb) containing solder possibly being inadvertently mixed on product soldered with tin-bismuth solder because there is a lead-bismuth combination that has a very low melting temperature around 98C.  Even today there is still SnPb solder being used for very high reliability products and by the military.  As Andy indicated in the past we had done failure analysis on telecommunication devices that had their components solder with traditional SAC Pb-Free solders but had very complicated heat and electrical shielding soldered using tin-bismuth solder.  The solder wetting on thawt product to the shielding was very poor and many cracks in shielding solder joints had been observed after the product had been subjected to mechanical testing.


Regards,
George Michael Wenger
  (732)-309-8964 (Mobile)



-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of David Hillman
Sent: Tuesday, February 14, 2017 7:02 PM
To: [log in to unmask]
Subject: Re: [TN] New Solder Alloy

Hi TechNet - I will echo Andy's comments, the SnBi solder alloy system may have some application in some products but a number of solder alloys in the SnBi alloy family have been extensively investigated and found to not be applicable for a large segment of high performance product types/use environments.

Dave

On Tue, Feb 14, 2017 at 2:06 PM, Giamis, Andy <[log in to unmask]>
wrote:

> Interesting.
> I tore apart a certain smart phone a few years back and saw that they
> attach heat shields/heat spreaders to the PCB edge with Sn-Bi.   The PCBA
> was amazing but I thought the Sn-Bi solder joints had wetting issues 
> and many of the solder joints were cracked.  Sn-Bi seems to be rather brittle.
> It would be interesting to see how this particular alloy performs.
>
>
>
> -----Original Message-----
> From: TechNet [mailto:[log in to unmask]] On Behalf Of Mike Buetow
> Sent: Tuesday, February 14, 2017 11:38 AM
> To: [log in to unmask]
> Subject: Re: [TN] New Solder Alloy
>
> I have been in touch with Lenovo about the alloy, which is a 
> tin-bismuth alloy developed in concert with Alpha and Senju. There's 
> some info in the link below based on what I've learned.
> http://circuitsassembly.com/ca/editorial/menu-news/27004-
> new-lenovo-lts-lowers-melting-temp-cuts-co2-emissions.html
> Best,
> Mike
> -------- Original message --------From: "Vargas, Stephen M" < 
> [log in to unmask]> Date: 2/14/17  9:19 AM  (GMT-08:00) To:
> [log in to unmask] Subject: [TN] New Solder Alloy Got news of this from a 
> colleague. Interesting... would love to hear comments from the TechNet 
> group.
>
> http://news.lenovo.com/news-releases/lenovo-announces-
> breakthrough-innovative-pc-manufacturing-process.htm
>
> Regards,
> Steve Vargas
>