How can I possibly follow that pun-filled message?
Yes, I do feel that the cooling rates effect changes in grain structure
formulation, which potentially could impact solder joint integrity and
long term reliability. Solder likes being heated and cooled fast. If
it weren't for fluxes and components and circuit boards, reflow profiles
would go straight up and down. In general, the faster the cool down
rate, the better (only in terms of the solder!). You'll notice shinier
joints as a result of a tighter grain structure that way.
Dave
-----Original Message-----
From: Whittaker, Dewey (AZ75) [mailto:[log in to unmask]]
Sent: Wednesday, August 03, 2005 4:29 PM
To: (Leadfree Electronics Assembly Forum); David Suraski
Subject: RE: [LF] 96.5% Tin / 3.5% Silver vs. SAC305
I find myself going through 3 different fatigue phases, also; morning;
noon; and night. No wonder I'm ready to hit the SAC by the end of the
evening.
Now that I've slept on it, do you feel the cooling rates effect changes
in grain structure formulation, which potentially could impact solder
joint integrity and long term reliability?
Dewey
-----Original Message-----
From: Leadfree [mailto:[log in to unmask]] On Behalf Of David Suraski
Sent: Wednesday, August 03, 2005 1:00 PM
To: [log in to unmask]
Subject: Re: [LF] 96.5% Tin / 3.5% Silver vs. SAC305
The alloy's microstructure goes through three different phases depending
on the cooling rate that it is exposed to. These phases have different
fatigue characteristics
This issue raises the practical concerns that, depending on the size and
location of a component on a board which will effect cooling rates,
structural weaknesses could actually occur in the solder interconnect,
leading to field failure.
-----Original Message-----
From: Leadfree [mailto:[log in to unmask]] On Behalf Of Richard Kraszewski
Sent: Wednesday, August 03, 2005 3:30 PM
To: [log in to unmask]
Subject: Re: [LF] 96.5% Tin / 3.5% Silver vs. SAC305
Phase Change? Can you elaborate please or send me an appropriate link?
Rich Kraszewski
Advanced Manufacturing Engineer - KEDS
Phone: 260.925.8719
-----Original Message-----
From: Leadfree [mailto:[log in to unmask]] On Behalf Of David Suraski
Sent: Wednesday, August 03, 2005 1:50 PM
To: [log in to unmask]
Subject: Re: [LF] 96.5% Tin / 3.5% Silver vs. SAC305
... and don't forget the silver phase change problems and poorer
mechanical fatigue resistance as compared to Sn/Ag/Cu.
Regards,
David Suraski
AIM
-----Original Message-----
From: Leadfree [mailto:[log in to unmask]] On Behalf Of MA/NY DDave
Sent: Wednesday, August 03, 2005 2:38 PM
To: [log in to unmask]
Subject: Re: [LF] 96.5% Tin / 3.5% Silver vs. SAC305
Hi KEDS-Rich, John, SPVC, IPC LF Listservers
Stopping for a minute on this fun discussion/learning experience.
If you decide to use 96.5Sn you do know that your soldering temperature
will be higher and you might have component MSL problems. I know it is
only a few degrees yet you don't have lots of margin on some of your
products.
YiEngr, MA/NY DDave
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