I think you summarized that very well, Dave! Thanks. I am training our engineers today so I'm away from my desk, hence my delayed responses.
I don't have any references to how much silver is too much, but I do know that there are several papers out there that discuss this. It is not so much the amount of silver all by itself, however. Some applications use 100% silver solder, as an example. The silver becomes an issue depending on how it affects the particular alloy of the whole finished solder joint in its entirety. Very, very minor doping of either Sn63 or Sn100 or SAC solders with even 1% silver, or for that matter, trace amounts of germanium, nickel, or other popular dopants can have huge impacts on the overall finished solder joint characteristics. Adding 2% silver to a Sn63 solder joint may not change its characteristics radically, but it will certainly change its appearance. Operators scrub away at it trying to make it shiny like the SJs they are used to seeing, but in truth there is absolutely nothing "wrong" with these "dull" or "cold"-looking solder joints from a reliability standpoint, as Dave noted.
In Gil's particular situation as described, I was just saying that there is no point in adding any additional silver by using Sn62 solder; nothing will be gained.
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of David Hillman
Sent: Wednesday, March 06, 2019 8:45 AM
To: [log in to unmask]
Subject: Re: [TN] [External] [TN] SnAg component finish with SnPb solder past
Hi Gil - Sn62 solder which contain 2% silver content, was originally used
to slow down the diffusion of silver containing component termination
finishes. Silver diffuses very quickly into solder and having some silver
content in the solder alloy itself modifies those diffusion kinetics. The
introduction of copper or nickel barrier layers on component terminations
reduced/eliminated the need for this technique. The addition of silver does
slightly improve the reliability of solder joints but the cost of silver in
the solder alloy can be a negative for many companies. Bottom line - unless
you have a large input of silver (XX%) into a solder joint, silver will not
result in solder joint integrity degradation.
Richard - any additional thoughts?
Dave
On Wed, Mar 6, 2019 at 8:11 AM Gil Zilber MTH <[log in to unmask]> wrote:
> Hi Richard,
> One more question. You said, "But in this case using Sn62 would add
> another 1% of silver to the solder joints and you would not want that."
> What is the reason? Can I understand that components that have higher
> Silver contents in their surface finish could have a reliability issue?
>
> Regards,
> Gil
> -----Original Message-----
> From: Stadem, Richard D [mailto:[log in to unmask]]
> Sent: Wednesday, March 6, 2019 3:53 PM
> To: Gil Zilber MTH <[log in to unmask]>; TechNet E-Mail Forum <
> [log in to unmask]>
> Subject: RE: [External] [TN] SnAg component finish with SnPb solder past
>
> I don't think so. Sn62 would be better if the part was being soldered to a
> surface that is sintered silver, to help limit leaching of the sintered
> silver surface. But in this case using Sn62 would add another 1% of silver
> to the solder joints and you would not want that. I would use Sn63.
>
> -----Original Message-----
> From: Gil Zilber MTH [mailto:[log in to unmask]]
> Sent: Wednesday, March 06, 2019 7:47 AM
> To: Stadem, Richard D; TechNet E-Mail Forum
> Subject: RE: [External] [TN] SnAg component finish with SnPb solder past
>
> Thanks Richard,
> I was hesitated only because of the Silver. Will it be better to use Sn62
> and not Sn63?
> Thanks,
> Gil
>
> -----Original Message-----
> From: Stadem, Richard D [mailto:[log in to unmask]]
> Sent: Wednesday, March 6, 2019 3:16 PM
> To: Gil Zilber MTH <[log in to unmask]>; TechNet E-Mail Forum <
> [log in to unmask]>
> Subject: RE: [External] [TN] SnAg component finish with SnPb solder past
>
> Gil,
> I don't really see an issue with soldering that part. It is basically a
> SOT89 package with compliant leads and a large bottom pad. There would be
> plenty of solder volume to absorb the small amount of silver, and the part
> is not going to be affected by huge delta Ts as it is quite small. Nothing
> jumps out at me that indicates a potential issue. We solder lots of those
> and I have not seen any problems. You may see some voids in an X-ray
> because of the large flat pad, but they do not typically pose any
> reliability issue. Is there anything that is making you hesitate?
> Odin
>
> -----Original Message-----
> From: Gil Zilber MTH [mailto:[log in to unmask]]
> Sent: Wednesday, March 06, 2019 1:50 AM
> To: Stadem, Richard D; TechNet E-Mail Forum
> Subject: RE: [External] [TN] SnAg component finish with SnPb solder past
>
> Hi,
> It is a monolithic amplifier (GVA-84+ from mini-circuits) case style:
> DF782 Thanks, Gil
>
> -----Original Message-----
> From: Stadem, Richard D [mailto:[log in to unmask]]
> Sent: Tuesday, March 5, 2019 8:39 PM
> To: TechNet E-Mail Forum <[log in to unmask]>; Gil Zilber MTH <
> [log in to unmask]>
> Subject: RE: [External] [TN] SnAg component finish with SnPb solder past
>
> What type of component is it?
>
> -----Original Message-----
> From: TechNet [mailto:[log in to unmask]] On Behalf Of Gil Zilber MTH
> Sent: Tuesday, March 05, 2019 11:40 AM
> To: [log in to unmask]
> Subject: Re: [TN] [External] [TN] SnAg component finish with SnPb solder
> past
>
> Hi dave,
> It is 1-3% silver.
> Thanks.
> Gil
>
>
> -------- הודעה מקורית --------
> מאת: David Hillman <[log in to unmask]>
> תאריך: 4.3.2019 23:12 (GMT+02:00)
> אל: TechNet E-Mail Forum <[log in to unmask]>, Gil Zilber MTH <
> [log in to unmask]>
> נושא: Re: [External] [TN] SnAg component finish with SnPb solder past
>
> Hi Gil - what is the composition of the SnAg plating?
>
> Dave Hillman
> Collins Aerospace
> [log in to unmask]<mailto:[log in to unmask]>
>
> On Mon, Mar 4, 2019 at 9:23 AM Gil Zilber MTH <[log in to unmask]<mailto:
> [log in to unmask]>> wrote:
> Hello,
> Does anyone know if there is an issue of soldering components that have
> SnAg finish with SnPb solder paste?
>
> Thanks,
> Gil Zilber
> Process Engineer at IAI
>
> ***********************************************************************************************
> Please consider the environment before printing this email ! The
> information contained in this communication is proprietary to Israel
> Aerospace Industries Ltd. and/or third parties, may contain confidential or
> privileged information, and is intended only for the use of the intended
> addressee thereof. If you are not the intended addressee, please be aware
> that any use, disclosure, distribution and/or copying of this communication
> is strictly prohibited. If you receive this communication in error, please
> notify the sender immediately and delete it from your computer. Thank you.
> Visit us at:
> https://urldefense.proofpoint.com/v2/url?u=http-3A__www.iai.co.il&d=DwIFAg&c=ilBQI1lupc9Y65XwNblLtw&r=qMshjwqeixvQjs1qYTl8aRebuaqi25nLzYlpmDF6tjI&m=1EcAWfE8N3tV5N8R-_vKcpyy81cpdr0C9ZtM2gH9g5I&s=78ShPh3PR8932eqz4gIGKUdnQNtQMVLLQmZgbjmSi08&e=
>
> Default Profile 60
> ***********************************************************************************************
> Please consider the environment before printing this email ! The
> information contained in this communication is proprietary to Israel
> Aerospace Industries Ltd. and/or third parties, may contain confidential or
> privileged information, and is intended only for the use of the intended
> addressee thereof. If you are not the intended addressee, please be aware
> that any use, disclosure, distribution and/or copying of this communication
> is strictly prohibited. If you receive this communication in error, please
> notify the sender immediately and delete it from your computer. Thank you.
> Visit us at:
> https://urldefense.proofpoint.com/v2/url?u=http-3A__www.iai.co.il&d=DwIF_Q&c=ilBQI1lupc9Y65XwNblLtw&r=qMshjwqeixvQjs1qYTl8aRebuaqi25nLzYlpmDF6tjI&m=svFl4S5-YN9cYj2qZTq2U9Cx4TRbJRMuEOO6KMO6pUk&s=6ltbkJ-f1leIylVqvupN8FO1LensyRIsdias5VOWYCA&e=
>
> Default Profile 60
>
> ***********************************************************************************************
> Please consider the environment before printing this email ! The
> information contained in this communication is proprietary to Israel
> Aerospace Industries Ltd. and/or third parties, may contain confidential or
> privileged information, and is intended only for the use of the intended
> addressee thereof. If you are not the intended addressee, please be aware
> that any use, disclosure, distribution and/or copying of this communication
> is strictly prohibited. If you receive this communication in error, please
> notify the sender immediately and delete it from your computer. Thank you.
> Visit us at:
> https://urldefense.proofpoint.com/v2/url?u=http-3A__www.iai.co.il&d=DwIF_Q&c=ilBQI1lupc9Y65XwNblLtw&r=qMshjwqeixvQjs1qYTl8aRebuaqi25nLzYlpmDF6tjI&m=svFl4S5-YN9cYj2qZTq2U9Cx4TRbJRMuEOO6KMO6pUk&s=6ltbkJ-f1leIylVqvupN8FO1LensyRIsdias5VOWYCA&e=
>
> Default Profile 61
>
> ***********************************************************************************************
> Please consider the environment before printing this email ! The
> information contained in this communication is proprietary to Israel
> Aerospace Industries Ltd. and/or third parties, may contain confidential or
> privileged information, and is intended only for the use of the intended
> addressee thereof. If you are not the intended addressee, please be aware
> that any use, disclosure, distribution and/or copying of this communication
> is strictly prohibited. If you receive this communication in error, please
> notify the sender immediately and delete it from your computer. Thank you.
> Visit us at:
> https://urldefense.proofpoint.com/v2/url?u=http-3A__www.iai.co.il&d=DwIF_Q&c=ilBQI1lupc9Y65XwNblLtw&r=qMshjwqeixvQjs1qYTl8aRebuaqi25nLzYlpmDF6tjI&m=svFl4S5-YN9cYj2qZTq2U9Cx4TRbJRMuEOO6KMO6pUk&s=6ltbkJ-f1leIylVqvupN8FO1LensyRIsdias5VOWYCA&e=
>
> Default Profile 61
>
> ***********************************************************************************************
> Please consider the environment before printing this email ! The
> information contained in this communication is proprietary to Israel
> Aerospace Industries Ltd. and/or third parties, may contain confidential or
> privileged information, and is intended only for the use of the intended
> addressee thereof. If you are not the intended addressee, please be aware
> that any use, disclosure, distribution and/or copying of this communication
> is strictly prohibited. If you receive this communication in error, please
> notify the sender immediately and delete it from your computer. Thank you.
> Visit us at:
> https://urldefense.proofpoint.com/v2/url?u=http-3A__www.iai.co.il&d=DwIF_Q&c=ilBQI1lupc9Y65XwNblLtw&r=qMshjwqeixvQjs1qYTl8aRebuaqi25nLzYlpmDF6tjI&m=svFl4S5-YN9cYj2qZTq2U9Cx4TRbJRMuEOO6KMO6pUk&s=6ltbkJ-f1leIylVqvupN8FO1LensyRIsdias5VOWYCA&e=
>
|
