But Bob, someone needs to go tell CALCE that there's equal or better
reliability with lead-free, just ask Motorola, they have about 10 years of
field data, and they can't forget about the trillions of dollars worth of
products manufactured since RoHS was enacted, with no major reliability
problems.
Hmmmm, I guess CALCE just didn't listen. Boy! Them guys can be stubborn like
that can't they?
Steve
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Bob Landman
Sent: Thursday, August 25, 2011 11:11 AM
To: [log in to unmask]
Subject: [TN] CALCE Findings on Toyota's Unintended Acceleration
New Findings on Toyota's Unintended Acceleration
Wednesday, August 24, 2011 | Safety Research & Strategies, Inc.
"In our analysis, a significant number of tin whiskers were found. Using the
CALCE Whisker Risk Calculator (CALCE) Tin Whisker Risk Calculator, 2005) to
assess the failure risk posed by observed tin whisker formation on the
conductor pairs, it was determined that the potential for a tin whisker
shorting failure was 140/1 million. Considering the number of vehicles on
the road, it is expected that this would present a significant safety
hazard."
In addition to tin whisker formation in the APPS, the CALCE researchers
found the potential for tin whisker formation in the ECM (engine control
module):
"The ECM contains surface mount electronic devices connected with tin-lead
solder to a multilayer PCB. . Interconnect terminals of the perimeter leaded
devices were found to be plated with tin. In addition, tin plating was found
on terminal pins of the edge connections. As previously discussed,
tin-finished leads can grow tin whiskers which can lead to unintended
electrical shorts."
"We know whiskers can form on tin finished terminals," Osterman said. "In
this case, Toyota has tin plating in a rather sensitive area, where the
system relies on changes in resistance to provide a signal for
acceleration."
In their discussion about the printed circuit board manufacturing processes
of Toyota Camrys, CALCE scientists questioned the lack of a safety standard
regarding automotive electronics, given broad range of whisker-induced
failures. They were openly critical of NHTSA's lack of action.
"It is highly likely that tin whiskers could induce a failure that is later
undetected. For this reason, best practices for electronics design stipulate
that tin not be used as a plating material. It is very questionable why the
National Highway Traffic Safety Administration, with a stated mission to
'save lives, prevent injuries and reduce economic costs due to road traffic
crashes, through education, research, safety standards, and enforcement
activity,' has not come out with a requirement that no electronics use pure
tin as a material component, since the potential for tin whiskers presents
an unreasonable and unnecessary risk."
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