Amol,

I am not sure you are going to get a definitive answer to that given the
IPC document shortfall.

I suspect that over the next 6 months your e-mail may be the tip of a
lead-free solder joint quality Ice Berg.

John

John Burke
Senior Manager - Operations , Optichron
[log in to unmask]
W: 510 249 5233
M: 408 515 4992
http://www.optichron.com
Profile: https://www.linkedin.com/e/fps/2665502/

-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Kane, Amol (349)
Sent: Friday, February 17, 2006 10:08 AM
To: [log in to unmask]
Subject: [TN] Big Holes (no Pun intended) in the IPC610D Criteria for
Shrink/tear holes

Dear Technetters,
I have Immersion Ag and Immersion Sn LF boards that were waved using
SAC305 alloy. I have a lot of tears/shrink voids in the waved
connections. I am aware that SAC305 in wave has a propensity of shrink
tears/voids due to the non eutectic property of SAC.

IPC 610 Rev D 5.2.11 says that as long as the bottom of the tear is
visible, and the tear does not contact any lead land or barrel wall, it
is acceptable. My issue is that clearly IPC did not put any thought in
this statement. For starters, what magnification should I use for
inspection of this tear? The physical appearance of these tears is such
that it is impossible to be able to see the bottom (they branch out
inside in a zigzag manner, and are seldom just straight down). The
location of these tears may prove conductive to crack propagation during
thermal cycling.

In view of this uncertainty, how do I pass these joints and ship the
boards (Currently, I am in the process of x-sectioning the joints to
determine the distribution and extent of these cracks in the solder to
gather more info and pass/fail the boards based on it)

Any thoughts everybody???

Regards,
Amol Kane
M.S (Industrial Eng.)
Process Engineer
Harvard Custom Manufacturing 
941 Route 38  Owego, NY 13827
Phone: (607) 687-7669 x349
[log in to unmask]

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